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Evaluation Of The Substrate Envelope Hypothesis For Inhibitors Of Hiv-1 Protease, Sripriya Chellappan, Visvaldas Kairys, Miguel Fernandes, Celia Schiffer, Michael Gilson
Evaluation Of The Substrate Envelope Hypothesis For Inhibitors Of Hiv-1 Protease, Sripriya Chellappan, Visvaldas Kairys, Miguel Fernandes, Celia Schiffer, Michael Gilson
Celia A. Schiffer
Crystallographic data show that various substrates of HIV protease occupy a remarkably uniform region within the binding site; this region has been termed the substrate envelope. It has been suggested that an inhibitor that fits within the substrate envelope should tend to evade viral resistance because a protease mutation that reduces the affinity of the inhibitor will also tend to reduce the affinity of substrate, and will hence decrease the activity of the enzyme. Accordingly, inhibitors that fit the substrate envelope better should be less susceptible to clinically observed resistant mutations, since these must also allow substrates to bind. The …
Discovery Of Hiv-1 Protease Inhibitors With Picomolar Affinities Incorporating N-Aryl-Oxazolidinone-5-Carboxamides As Novel P2 Ligands, Akbar Ali, G. S. Kiran Kumar Reddy, Hong Cao, Saima Anjum, Madhavi Nalam, Celia Schiffer, Tariq Rana
Discovery Of Hiv-1 Protease Inhibitors With Picomolar Affinities Incorporating N-Aryl-Oxazolidinone-5-Carboxamides As Novel P2 Ligands, Akbar Ali, G. S. Kiran Kumar Reddy, Hong Cao, Saima Anjum, Madhavi Nalam, Celia Schiffer, Tariq Rana
Celia A. Schiffer
Here, we describe the design, synthesis, and biological evaluation of novel HIV-1 protease inhibitors incorporating N-phenyloxazolidinone-5-carboxamides into the (hydroxyethylamino)sulfonamide scaffold as P2 ligands. Series of inhibitors with variations at the P2 phenyloxazolidinone and the P2' phenylsulfonamide moieties were synthesized. Compounds with the (S)-enantiomer of substituted phenyloxazolidinones at P2 show highly potent inhibitory activities against HIV-1 protease. The inhibitors possessing 3-acetyl, 4-acetyl, and 3-trifluoromethyl groups at the phenyl ring of the oxazolidinone fragment are the most potent in each series, with K(i) values in the low picomolar (pM) range. The electron-donating groups 4-methoxy and 1,3-dioxolane are preferred at P2' phenyl ring, …
Association Of A Novel Human Immunodeficiency Virus Type 1 Protease Substrate Cleft Mutation, L23i, With Protease Inhibitor Therapy And In Vitro Drug Resistance, Elizabeth Johnston, Mark Winters, Soo-Yon Rhee, Thomas Merigan, Celia Schiffer, Robert Shafer
Association Of A Novel Human Immunodeficiency Virus Type 1 Protease Substrate Cleft Mutation, L23i, With Protease Inhibitor Therapy And In Vitro Drug Resistance, Elizabeth Johnston, Mark Winters, Soo-Yon Rhee, Thomas Merigan, Celia Schiffer, Robert Shafer
Celia A. Schiffer
We observed a previously uncharacterized mutation in the protease substrate cleft, L23I, in 31 of 4,303 persons undergoing human immunodeficiency virus type 1 genotypic resistance testing. In combination with V82I, L23I was associated with a sevenfold reduction in nelfinavir susceptibility and a decrease in replication capacity. In combination with other drug resistance mutations, L23I was associated with multidrug resistance and a compensatory increase in replication capacity.
Co-Evolution Of Nelfinavir-Resistant Hiv-1 Protease And The P1-P6 Substrate, Madhavi Kolli, Stephane Lastere, Celia Schiffer
Co-Evolution Of Nelfinavir-Resistant Hiv-1 Protease And The P1-P6 Substrate, Madhavi Kolli, Stephane Lastere, Celia Schiffer
Celia A. Schiffer
The selective pressure of the competitive protease inhibitors causes both HIV-1 protease and occasionally its substrates to evolve drug resistance. We hypothesize that this occurs particularly in substrates that protrude beyond the substrate envelope and contact residues that mutate in response to a particular protease inhibitor. To validate this hypothesis, we analyzed substrate and protease sequences for covariation. Using the chi2 test, we show a positive correlation between the nelfinavir-resistant D30N/N88D protease mutations and mutations at the p1-p6 cleavage site as compared to the other cleavage sites. Both nelfinavir and the substrate p1-p6 protrude beyond the substrate envelope and contact …
Substrate Shape Determines Specificity Of Recognition For Hiv-1 Protease: Analysis Of Crystal Structures Of Six Substrate Complexes, Moses Prabu-Jeyabalan, Ellen Nalivaika, Celia Schiffer
Substrate Shape Determines Specificity Of Recognition For Hiv-1 Protease: Analysis Of Crystal Structures Of Six Substrate Complexes, Moses Prabu-Jeyabalan, Ellen Nalivaika, Celia Schiffer
Celia A. Schiffer
The homodimeric HIV-1 protease is the target of some of the most effective antiviral AIDS therapy, as it facilitates viral maturation by cleaving ten asymmetric and nonhomologous sequences in the Gag and Pol polyproteins. Since the specificity of this enzyme is not easily determined from the sequences of these cleavage sites alone, we solved the crystal structures of complexes of an inactive variant (D25N) of HIV-1 protease with six peptides that correspond to the natural substrate cleavage sites. When the protease binds to its substrate and buries nearly 1000 A2 of surface area, the symmetry of the protease is broken, …
Rationale For More Diverse Inhibitors In Competition With Substrates In Hiv-1 Protease, Nevra Ozer, Celia Schiffer, Turkan Haliloglu
Rationale For More Diverse Inhibitors In Competition With Substrates In Hiv-1 Protease, Nevra Ozer, Celia Schiffer, Turkan Haliloglu
Celia A. Schiffer
The structural fluctuations of HIV-1 protease in interaction with its substrates versus inhibitors were analyzed using the anisotropic network model. The directions of fluctuations in the most cooperative functional modes differ mainly around the dynamically key regions, i.e., the hinge axes, which appear to be more flexible in substrate complexes. The flexibility of HIV-1 protease is likely optimized for the substrates' turnover, resulting in substrate complexes being dynamic. In contrast, in an inhibitor complex, the inhibitor should bind and lock down to inactivate the active site. Protease and ligands are not independent. Substrates are also more flexible than inhibitors and …
Substrate Specificity In Hiv-1 Protease By A Biased Sequence Search Method, Nevra Ozer, Turkan Haliloglu, Celia Schiffer
Substrate Specificity In Hiv-1 Protease By A Biased Sequence Search Method, Nevra Ozer, Turkan Haliloglu, Celia Schiffer
Celia A. Schiffer
Drug resistance in HIV-1 protease can also occasionally confer a change in the substrate specificity. Through the use of computational techniques, a relationship can be determined between the substrate sequence and three-dimensional structure of HIV-1 protease, and be utilized to predict substrate specificity. In this study, we introduce a biased sequence search threading (BSST) methodology to analyze the preferences of substrate positions and correlations between them that might also identify which positions within known substrates can likely tolerate sequence variability and which cannot. The potential sequence space was efficiently explored using a low-resolution knowledge-based scoring function. The low-energy substrate sequences …
Crystal Structure Of Lysine Sulfonamide Inhibitor Reveals The Displacement Of The Conserved Flap Water Molecule In Human Immunodeficiency Virus Type 1 Protease, Madhavi Nalam, Anik Peeters, Tim Jonckers, Inge Dierynck, Celia Schiffer
Crystal Structure Of Lysine Sulfonamide Inhibitor Reveals The Displacement Of The Conserved Flap Water Molecule In Human Immunodeficiency Virus Type 1 Protease, Madhavi Nalam, Anik Peeters, Tim Jonckers, Inge Dierynck, Celia Schiffer
Celia A. Schiffer
Human immunodeficiency virus type 1 (HIV-1) protease has been continuously evolving and developing resistance to all of the protease inhibitors. This requires the development of new inhibitors that bind to the protease in a novel fashion. Most of the inhibitors that are on the market are peptidomimetics, where a conserved water molecule mediates hydrogen bonding interactions between the inhibitors and the flaps of the protease. Recently a new class of inhibitors, lysine sulfonamides, was developed to combat the resistant variants of HIV protease. Here we report the crystal structure of a lysine sulfonamide. This inhibitor binds to the active site …
Additivity In The Analysis And Design Of Hiv Protease Inhibitors, Robert Jorissen, G. S. Kiran Kumar Reddy, Akbar Ali, Michael Altman, Sripriya Chellappan, Saima Anjum, Bruce Tidor, Celia Schiffer, Tariq Rana, Michael Gilson
Additivity In The Analysis And Design Of Hiv Protease Inhibitors, Robert Jorissen, G. S. Kiran Kumar Reddy, Akbar Ali, Michael Altman, Sripriya Chellappan, Saima Anjum, Bruce Tidor, Celia Schiffer, Tariq Rana, Michael Gilson
Celia A. Schiffer
We explore the applicability of an additive treatment of substituent effects to the analysis and design of HIV protease inhibitors. Affinity data for a set of inhibitors with a common chemical framework were analyzed to provide estimates of the free energy contribution of each chemical substituent. These estimates were then used to design new inhibitors whose high affinities were confirmed by synthesis and experimental testing. Derivations of additive models by least-squares and ridge-regression methods were found to yield statistically similar results. The additivity approach was also compared with standard molecular descriptor-based QSAR; the latter was not found to provide superior …
Structural Basis For Coevolution Of A Human Immunodeficiency Virus Type 1 Nucleocapsid-P1 Cleavage Site With A V82a Drug-Resistant Mutation In Viral Protease, Moses Prabu-Jeyabalan, Ellen A. Nalivaika, Nancy M. King, Celia A. Schiffer
Structural Basis For Coevolution Of A Human Immunodeficiency Virus Type 1 Nucleocapsid-P1 Cleavage Site With A V82a Drug-Resistant Mutation In Viral Protease, Moses Prabu-Jeyabalan, Ellen A. Nalivaika, Nancy M. King, Celia A. Schiffer
Celia A. Schiffer
Maturation of human immunodeficiency virus (HIV) depends on the processing of Gag and Pol polyproteins by the viral protease, making this enzyme a prime target for anti-HIV therapy. Among the protease substrates, the nucleocapsid-p1 (NC-p1) sequence is the least homologous, and its cleavage is the rate-determining step in viral maturation. In the other substrates of HIV-1 protease, P1 is usually either a hydrophobic or an aromatic residue, and P2 is usually a branched residue. NC-p1, however, contains Asn at P1 and Ala at P2. In response to the V82A drug-resistant protease mutation, the P2 alanine of NC-p1 mutates to valine …
How Does A Symmetric Dimer Recognize An Asymmetric Substrate? A Substrate Complex Of Hiv-1 Protease, Moses Prabu-Jeyabalan, Ellen Nalivaika, Celia Schiffer
How Does A Symmetric Dimer Recognize An Asymmetric Substrate? A Substrate Complex Of Hiv-1 Protease, Moses Prabu-Jeyabalan, Ellen Nalivaika, Celia Schiffer
Celia A. Schiffer
The crystal structure of an actual HIV-1 protease-substrate complex is presented at 2.0 A resolution (R-value of 19.7 % (R(free) 23.3 %)) between an inactive variant (D25N) of HIV-1 protease and a long substrate peptide, Lys-Ala-Arg-Val-Leu-Ala-Glu-Ala-Met-Ser, which covers a full binding epitope of capsid(CA)-p2, cleavage site. The substrate peptide is asymmetric in both size and charge distribution. To accommodate this asymmetry the two protease monomers adopt different conformations burying a total of 1038 A(2) of surface area at the protease-substrate interface. The specificity for the CA-p2 substrate peptide is mainly hydrophobic, as most of the hydrogen bonds are made with …
Toward The Design Of Mutation-Resistant Enzyme Inhibitors: Further Evaluation Of The Substrate Envelope Hypothesis, Visvaldas Kairys, Michael Gilson, Viney Lather, Celia Schiffer, Miguel Fernandes
Toward The Design Of Mutation-Resistant Enzyme Inhibitors: Further Evaluation Of The Substrate Envelope Hypothesis, Visvaldas Kairys, Michael Gilson, Viney Lather, Celia Schiffer, Miguel Fernandes
Celia A. Schiffer
Previous studies have shown the usefulness of the substrate envelope concept in the analysis and prediction of drug resistance profiles for human immunodeficiency virus protease mutants. This study tests its applicability to several other therapeutic targets: Abl kinase, chitinase, thymidylate synthase, dihydrofolate reductase, and neuraminidase. For the targets where many (> or =6) mutation data are available to compute the average mutation sensitivity of inhibitors, the total volume of an inhibitor molecule that projects outside the substrate envelope V(out), is found to correlate with average mutation sensitivity. Analysis of a locally computed volume suggests that the same correlation would hold …
Dynamics Of Preferential Substrate Recognition In Hiv-1 Protease: Redefining The Substrate Envelope, Aysegul Ozen, Turkan Haliloglu, Celia Schiffer
Dynamics Of Preferential Substrate Recognition In Hiv-1 Protease: Redefining The Substrate Envelope, Aysegul Ozen, Turkan Haliloglu, Celia Schiffer
Celia A. Schiffer
Human immunodeficiency virus type 1 (HIV-1) protease (PR) permits viral maturation by processing the gag and gag-pro-pol polyproteins. HIV-1 PR inhibitors (PIs) are used in combination antiviral therapy but the emergence of drug resistance has limited their efficacy. The rapid evolution of HIV-1 necessitates consideration of drug resistance in novel drug design. Drug-resistant HIV-1 PR variants no longer inhibited efficiently, continue to hydrolyze the natural viral substrates. Though highly diverse in sequence, the HIV-1 PR substrates bind in a conserved three-dimensional shape we termed the substrate envelope. Earlier, we showed that resistance mutations arise where PIs protrude beyond the substrate …
N88d Facilitates The Co-Occurrence Of D30n And L90m And The Development Of Multidrug Resistance In Hiv Type 1 Protease Following Nelfinavir Treatment Failure, Yumi Mitsuya, Mark Winters, W. Jeffrey Fessel, Soo-Yon Rhee, Leo Hurley, Michael Horberg, Celia Schiffer, Andrew Zolopa, Robert Shafer
N88d Facilitates The Co-Occurrence Of D30n And L90m And The Development Of Multidrug Resistance In Hiv Type 1 Protease Following Nelfinavir Treatment Failure, Yumi Mitsuya, Mark Winters, W. Jeffrey Fessel, Soo-Yon Rhee, Leo Hurley, Michael Horberg, Celia Schiffer, Andrew Zolopa, Robert Shafer
Celia A. Schiffer
Nelfinavir was once one of the most commonly used protease inhibitors (PIs). To investigate the genetic mechanisms of multidrug resistance in protease isolates with the primary nelfinavir resistance mutation D30N, we analyzed patterns of protease mutations in 582 viruses with D30N from 460 persons undergoing HIV-1 genotypic resistance testing at Stanford University Hospital from 1997 to 2005. Three patterns of mutational associations were identified. First, D30N was positively associated with N88D but negatively associated with N88S. Second, D30N and L90M were negatively associated except in the presence of N88D, which facilitated the co-occurrence of D30N and L90M. Third, D30N+N88D+L90M formed …
Cooperative Fluctuations Of Unliganded And Substrate-Bound Hiv-1 Protease: A Structure-Based Analysis On A Variety Of Conformations From Crystallography And Molecular Dynamics Simulations, Nese Kurt, Walter Scott, Celia Schiffer, Turkan Haliloglu
Cooperative Fluctuations Of Unliganded And Substrate-Bound Hiv-1 Protease: A Structure-Based Analysis On A Variety Of Conformations From Crystallography And Molecular Dynamics Simulations, Nese Kurt, Walter Scott, Celia Schiffer, Turkan Haliloglu
Celia A. Schiffer
The dynamics of HIV-1 protease, both in unliganded and substrate-bound forms have been analyzed by using an analytical method, Gaussian network model (GNM). The method is applied to different conformations accessible to the protein backbone in the native state, observed in crystal structures and snapshots from fully atomistic molecular dynamics (MD) simulation trajectories. The modes of motion obtained from GNM on different conformations of HIV-1 protease are conserved throughout the MD simulations. The flaps and 40's loop of the unliganded HIV-1 protease structure are identified as the most mobile regions. However, in the liganded structure these flaps lose mobility, and …
Design Of Mutation-Resistant Hiv Protease Inhibitors With The Substrate Envelope Hypothesis, Sripriya Chellappan, G. S. Kiran Kumar Reddy, Akbar Ali, Madhavi Nalam, Saima Anjum, Hong Cao, Visvaldas Kairys, Miguel Fernandes, Michael Altman, Bruce Tidor, Tariq Rana, Celia Schiffer, Michael Gilson
Design Of Mutation-Resistant Hiv Protease Inhibitors With The Substrate Envelope Hypothesis, Sripriya Chellappan, G. S. Kiran Kumar Reddy, Akbar Ali, Madhavi Nalam, Saima Anjum, Hong Cao, Visvaldas Kairys, Miguel Fernandes, Michael Altman, Bruce Tidor, Tariq Rana, Celia Schiffer, Michael Gilson
Celia A. Schiffer
There is a clinical need for HIV protease inhibitors that can evade resistance mutations. One possible approach to designing such inhibitors relies upon the crystallographic observation that the substrates of HIV protease occupy a rather constant region within the binding site. In particular, it has been hypothesized that inhibitors which lie within this region will tend to resist clinically relevant mutations. The present study offers the first prospective evaluation of this hypothesis, via computational design of inhibitors predicted to conform to the substrate envelope, followed by synthesis and evaluation against wild-type and mutant proteases, as well as structural studies of …
Computational Design And Experimental Study Of Tighter Binding Peptides To An Inactivated Mutant Of Hiv-1 Protease, Michael Altman, Ellen Nalivaika, Moses Prabu-Jeyabalan, Celia Schiffer, Bruce Tidor
Computational Design And Experimental Study Of Tighter Binding Peptides To An Inactivated Mutant Of Hiv-1 Protease, Michael Altman, Ellen Nalivaika, Moses Prabu-Jeyabalan, Celia Schiffer, Bruce Tidor
Celia A. Schiffer
Drug resistance in HIV-1 protease, a barrier to effective treatment, is generally caused by mutations in the enzyme that disrupt inhibitor binding but still allow for substrate processing. Structural studies with mutant, inactive enzyme, have provided detailed information regarding how the substrates bind to the protease yet avoid resistance mutations; insights obtained inform the development of next generation therapeutics. Although structures have been obtained of complexes between substrate peptide and inactivated (D25N) protease, thermodynamic studies of peptide binding have been challenging due to low affinity. Peptides that bind tighter to the inactivated protease than the natural substrates would be valuable …
Design And Synthesis Of Hiv-1 Protease Inhibitors Incorporating Oxazolidinones As P2/P2' Ligands In Pseudosymmetric Dipeptide Isosteres, G. S. Kiran Kumar Reddy, Akbar Ali, Madhavi Nalam, Saima Anjum, Hong Cao, Robin Nathans, Celia Schiffer, Tariq Rana
Design And Synthesis Of Hiv-1 Protease Inhibitors Incorporating Oxazolidinones As P2/P2' Ligands In Pseudosymmetric Dipeptide Isosteres, G. S. Kiran Kumar Reddy, Akbar Ali, Madhavi Nalam, Saima Anjum, Hong Cao, Robin Nathans, Celia Schiffer, Tariq Rana
Celia A. Schiffer
A series of novel HIV-1 protease inhibitors based on two pseudosymmetric dipeptide isosteres have been synthesized and evaluated. The inhibitors were designed by incorporating N-phenyloxazolidinone-5-carboxamides into the hydroxyethylene and (hydroxyethyl)hydrazine dipeptide isosteres as P2 and P2' ligands. Compounds with (S)-phenyloxazolidinones attached at a position proximal to the central hydroxyl group showed low nM inhibitory activities against wild-type HIV-1 protease. Selected compounds were further evaluated for their inhibitory activities against a panel of multidrug-resistant protease variants and for their antiviral potencies in MT-4 cells. The crystal structures of lopinavir (LPV) and two new inhibitors containing phenyloxazolidinone-based ligands in complex with wild-type …
Evaluating The Substrate-Envelope Hypothesis: Structural Analysis Of Novel Hiv-1 Protease Inhibitors Designed To Be Robust Against Drug Resistance, Madhavi Nalam, Akbar Ali, Michael Altman, G. S. Kiran Kumar Reddy, Sripriya Chellappan, Visvaldas Kairys, Aysegul Ozen, Hong Cao, Michael Gilson, Bruce Tidor, Tariq Rana, Celia Schiffer
Evaluating The Substrate-Envelope Hypothesis: Structural Analysis Of Novel Hiv-1 Protease Inhibitors Designed To Be Robust Against Drug Resistance, Madhavi Nalam, Akbar Ali, Michael Altman, G. S. Kiran Kumar Reddy, Sripriya Chellappan, Visvaldas Kairys, Aysegul Ozen, Hong Cao, Michael Gilson, Bruce Tidor, Tariq Rana, Celia Schiffer
Celia A. Schiffer
Drug resistance mutations in HIV-1 protease selectively alter inhibitor binding without significantly affecting substrate recognition and cleavage. This alteration in molecular recognition led us to develop the substrate-envelope hypothesis which predicts that HIV-1 protease inhibitors that fit within the overlapping consensus volume of the substrates are less likely to be susceptible to drug-resistant mutations, as a mutation impacting such inhibitors would simultaneously impact the processing of substrates. To evaluate this hypothesis, over 130 HIV-1 protease inhibitors were designed and synthesized using three different approaches with and without substrate-envelope constraints. A subset of 16 representative inhibitors with binding affinities to wild-type …
Mechanism Of Substrate Recognition By Drug-Resistant Human Immunodeficiency Virus Type 1 Protease Variants Revealed By A Novel Structural Intermediate, Moses Prabu-Jeyabalan, Ellen A. Nalivaika, Keith Romano, Celia A. Schiffer
Mechanism Of Substrate Recognition By Drug-Resistant Human Immunodeficiency Virus Type 1 Protease Variants Revealed By A Novel Structural Intermediate, Moses Prabu-Jeyabalan, Ellen A. Nalivaika, Keith Romano, Celia A. Schiffer
Celia A. Schiffer
Human immunodeficiency virus type 1 (HIV-1) protease processes and cleaves the Gag and Gag-Pol polyproteins, allowing viral maturation, and therefore is an important target for antiviral therapy. Ligand binding occurs when the flaps open, allowing access to the active site. This flexibility in flap geometry makes trapping and crystallizing structural intermediates in substrate binding challenging. In this study, we report two crystal structures of two HIV-1 protease variants bound with their corresponding nucleocapsid-p1 variant. One of the flaps in each of these structures exhibits an unusual "intermediate" conformation. Analysis of the flap-intermediate and flap-closed crystal structures reveals that the intermonomer …
Combating Susceptibility To Drug Resistance: Lessons From Hiv-1 Protease, Nancy King, Moses Prabu-Jeyabalan, Ellen Nalivaika, Celia Schiffer
Combating Susceptibility To Drug Resistance: Lessons From Hiv-1 Protease, Nancy King, Moses Prabu-Jeyabalan, Ellen Nalivaika, Celia Schiffer
Celia A. Schiffer
Drug resistance is a major obstacle in modern medicine. However, resistance is rarely considered in drug development and may inadvertently be facilitated, as many designed inhibitors contact residues that can mutate to confer resistance, without significantly impairing function. Contemporary drug design often ignores the detailed atomic basis for function and primarily focuses on disrupting the target's activity, which is necessary but not sufficient for developing a robust drug. In this study, we examine the impact of drug-resistant mutations in HIV-1 protease on substrate recognition and demonstrate that most primary active site mutations do not extensively contact substrates, but are critical …
Decomposing The Energetic Impact Of Drug Resistant Mutations In Hiv-1 Protease On Binding Drv, Yufeng Cai, Celia Schiffer
Decomposing The Energetic Impact Of Drug Resistant Mutations In Hiv-1 Protease On Binding Drv, Yufeng Cai, Celia Schiffer
Celia A. Schiffer
Darunavir (DRV) is a high affinity (4.5x10(-12) M, DeltaG = -15.2 kcal/mol) HIV-1 protease inhibitor. Two drug-resistant protease variants FLAP+ (L10I, G48V, I54V, V82A) and ACT (V82T, I84V) decrease the binding affinity with DRV by 1.0 kcal/mol and 1.6 kcal/mol respectively. In this study the absolute and relative binding free energies of DRV with wild-type protease, FLAP+ and ACT were calculated with MM-PB/GBSA and thermodynamic integration methods, respectively. Free energy decomposition elucidated that the mutations conferred resistance by distorting the active site of HIV-1 protease so that the residues that lost binding free energy were not limited to the sites …
Replacement Of The P1 Amino Acid Of Human Immunodeficiency Virus Type 1 Gag Processing Sites Can Inhibit Or Enhance The Rate Of Cleavage By The Viral Protease, Steve Pettit, Gavin Henderson, Celia Schiffer, Ronald Swanstrom
Replacement Of The P1 Amino Acid Of Human Immunodeficiency Virus Type 1 Gag Processing Sites Can Inhibit Or Enhance The Rate Of Cleavage By The Viral Protease, Steve Pettit, Gavin Henderson, Celia Schiffer, Ronald Swanstrom
Celia A. Schiffer
Processing of the human immunodeficiency virus type 1 (HIV-1) Gag precursor is highly regulated, with differential rates of cleavage at the five major processing sites to give characteristic processing intermediates. We examined the role of the P1 amino acid in determining the rate of cleavage at each of these five sites by using libraries of mutants generated by site-directed mutagenesis. Between 12 and 17 substitution mutants were tested at each P1 position in Gag, using recombinant HIV-1 protease (PR) in an in vitro processing reaction of radiolabeled Gag substrate. There were three sites in Gag (MA/CA, CA/p2, NC/p1) where one …
Hiv-1 Protease Inhibitors From Inverse Design In The Substrate Envelope Exhibit Subnanomolar Binding To Drug-Resistant Variants, Michael Altman, Akbar Ali, G. S. Kiran Kumar Reddy, Madhavi Nalam, Saima Anjum, Hong Cao, Sripriya Chellappan, Visvaldas Kairys, Miguel Fernandes, Michael Gilson, Celia Schiffer, Tariq Rana, Bruce Tidor
Hiv-1 Protease Inhibitors From Inverse Design In The Substrate Envelope Exhibit Subnanomolar Binding To Drug-Resistant Variants, Michael Altman, Akbar Ali, G. S. Kiran Kumar Reddy, Madhavi Nalam, Saima Anjum, Hong Cao, Sripriya Chellappan, Visvaldas Kairys, Miguel Fernandes, Michael Gilson, Celia Schiffer, Tariq Rana, Bruce Tidor
Celia A. Schiffer
The acquisition of drug-resistant mutations by infectious pathogens remains a pressing health concern, and the development of strategies to combat this threat is a priority. Here we have applied a general strategy, inverse design using the substrate envelope, to develop inhibitors of HIV-1 protease. Structure-based computation was used to design inhibitors predicted to stay within a consensus substrate volume in the binding site. Two rounds of design, synthesis, experimental testing, and structural analysis were carried out, resulting in a total of 51 compounds. Improvements in design methodology led to a roughly 1000-fold affinity enhancement to a wild-type protease for the …
The Effect Of Clade-Specific Sequence Polymorphisms On Hiv-1 Protease Activity And Inhibitor Resistance Pathways, Rajintha Bandaranayake, Madhavi Kolli, Nancy King, Ellen Nalivaika, Annie Heroux, Junko Kakizawa, Wataru Sugiura, Celia Schiffer
The Effect Of Clade-Specific Sequence Polymorphisms On Hiv-1 Protease Activity And Inhibitor Resistance Pathways, Rajintha Bandaranayake, Madhavi Kolli, Nancy King, Ellen Nalivaika, Annie Heroux, Junko Kakizawa, Wataru Sugiura, Celia Schiffer
Celia A. Schiffer
The majority of HIV-1 infections around the world result from non-B clade HIV-1 strains. The CRF01_AE (AE) strain is seen principally in Southeast Asia. AE protease differs by approximately 10% in amino acid sequence from clade B protease and carries several naturally occurring polymorphisms that are associated with drug resistance in clade B. AE protease has been observed to develop resistance through a nonactive-site N88S mutation in response to nelfinavir (NFV) therapy, whereas clade B protease develops both the active-site mutation D30N and the nonactive-site mutation N88D. Structural and biochemical studies were carried out with wild-type and NFV-resistant clade B …
Lack Of Synergy For Inhibitors Targeting A Multi-Drug-Resistant Hiv-1 Protease, Nancy King, Laurence Melnick, Moses Prabu-Jeyabalan, Ellen Nalivaika, Shiow-Shong Yang, Yun Gao, Xiaoyi Nie, Charles Zepp, Donald Heefner, Celia Schiffer
Lack Of Synergy For Inhibitors Targeting A Multi-Drug-Resistant Hiv-1 Protease, Nancy King, Laurence Melnick, Moses Prabu-Jeyabalan, Ellen Nalivaika, Shiow-Shong Yang, Yun Gao, Xiaoyi Nie, Charles Zepp, Donald Heefner, Celia Schiffer
Celia A. Schiffer
The three-dimensional structures of indinavir and three newly synthesized indinavir analogs in complex with a multi-drug-resistant variant (L63P, V82T, I84V) of HIV-1 protease were determined to approximately 2.2 A resolution. Two of the three analogs have only a single modification of indinavir, and their binding affinities to the variant HIV-1 protease are enhanced over that of indinavir. However, when both modifications were combined into a single compound, the binding affinity to the protease variant was reduced. On close examination, the structural rearrangements in the protease that occur in the tightest binding inhibitor complex are mutually exclusive with the structural rearrangements …
Hydrophobic Sliding: A Possible Mechanism For Drug Resistance In Human Immunodeficiency Virus Type 1 Protease, Jennifer Foulkes-Murzycki, Walter Scott, Celia Schiffer
Hydrophobic Sliding: A Possible Mechanism For Drug Resistance In Human Immunodeficiency Virus Type 1 Protease, Jennifer Foulkes-Murzycki, Walter Scott, Celia Schiffer
Celia A. Schiffer
Hydrophobic residues outside the active site of HIV-1 protease frequently mutate in patients undergoing protease inhibitor therapy; however, the mechanism by which these mutations confer drug resistance is not understood. From analysis of molecular dynamics simulations, 19 core hydrophobic residues appear to facilitate the conformational changes that occur in HIV-1 protease. The hydrophobic core residues slide by each other, exchanging one hydrophobic van der Waal contact for another, with little energy penalty, while maintaining many structurally important hydrogen bonds. Such hydrophobic sliding may represent a general mechanism by which proteins undergo conformational changes. Mutation of these residues in HIV-1 protease …
Viability Of A Drug-Resistant Human Immunodeficiency Virus Type 1 Protease Variant: Structural Insights For Better Antiviral Therapy, Moses Prabu-Jeyabalan, Ellen A. Nalivaika, Nancy M. King, Celia A. Schiffer
Viability Of A Drug-Resistant Human Immunodeficiency Virus Type 1 Protease Variant: Structural Insights For Better Antiviral Therapy, Moses Prabu-Jeyabalan, Ellen A. Nalivaika, Nancy M. King, Celia A. Schiffer
Celia A. Schiffer
Under the selective pressure of protease inhibitor therapy, patients infected with human immunodeficiency virus (HIV) often develop drug-resistant HIV strains. One of the first drug-resistant mutations to arise in the protease, particularly in patients receiving indinavir or ritonavir treatment, is V82A, which compromises the binding of these and other inhibitors but allows the virus to remain viable. To probe this drug resistance, we solved the crystal structures of three natural substrates and two commercial drugs in complex with an inactive drug-resistant mutant (D25N/V82A) HIV-1 protease. Through structural analysis and comparison of the protein-ligand interactions, we found that Val82 interacts more …
Discovery And Selection Of Tmc114, A Next Generation Hiv-1 Protease Inhibitor, Dominique Surleraux, Abdellah Tahri, Wim Verschueren, Geert Pille, Herman De Kock, Tim Jonckers, Anik Peeters, Sandra De Meyer, Hilde Azijn, Rudi Pauwels, Marie-Pierre De Bethune, Nancy King, Moses Prabu-Jeyabalan, Celia Schiffer, Piet Wigerinck
Discovery And Selection Of Tmc114, A Next Generation Hiv-1 Protease Inhibitor, Dominique Surleraux, Abdellah Tahri, Wim Verschueren, Geert Pille, Herman De Kock, Tim Jonckers, Anik Peeters, Sandra De Meyer, Hilde Azijn, Rudi Pauwels, Marie-Pierre De Bethune, Nancy King, Moses Prabu-Jeyabalan, Celia Schiffer, Piet Wigerinck
Celia A. Schiffer
The screening of known HIV-1 protease inhibitors against a panel of multi-drug-resistant viruses revealed the potent activity of TMC126 on drug-resistant mutants. In comparison to amprenavir, the improved affinity of TMC126 is largely the result of one extra hydrogen bond to the backbone of the protein in the P2 pocket. Modification of the substitution pattern on the phenylsulfonamide P2' substituent of TMC126 created an interesting SAR, with the close analogue TMC114 being found to have a similar antiviral activity against the mutant and the wild-type viruses. X-ray and thermodynamic studies on both wild-type and mutant enzymes showed an extremely high …
Role Of Invariant Thr80 In Human Immunodeficiency Virus Type 1 Protease Structure, Function, And Viral Infectivity, Jennifer E. Foulkes-Murzycki, Moses Prabu-Jeyabalan, Deyna Cooper, Gavin J. Henderson, Janera Harris, Ronald I. Swanstrom, Celia A. Schiffer
Role Of Invariant Thr80 In Human Immunodeficiency Virus Type 1 Protease Structure, Function, And Viral Infectivity, Jennifer E. Foulkes-Murzycki, Moses Prabu-Jeyabalan, Deyna Cooper, Gavin J. Henderson, Janera Harris, Ronald I. Swanstrom, Celia A. Schiffer
Celia A. Schiffer
Sequence variability associated with human immunodeficiency virus type 1 (HIV-1) is useful for inferring structural and/or functional constraints at specific residues within the viral protease. Positions that are invariant even in the presence of drug selection define critically important residues for protease function. While the importance of conserved active-site residues is easily understood, the role of other invariant residues is not. This work focuses on invariant Thr80 at the apex of the P1 loop of HIV-1, HIV-2, and simian immunodeficiency virus protease. In a previous study, we postulated, on the basis of a molecular dynamics simulation of the unliganded protease, …