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Articles 1 - 9 of 9
Full-Text Articles in Pharmacology
Structural Basis And Distal Effects Of Gag Substrate Coevolution In Drug Resistance To Hiv-1 Protease, Aysegul Ozen, Kuan-Hung Lin, Nese Yilmaz, Celia Schiffer
Structural Basis And Distal Effects Of Gag Substrate Coevolution In Drug Resistance To Hiv-1 Protease, Aysegul Ozen, Kuan-Hung Lin, Nese Yilmaz, Celia Schiffer
Celia A. Schiffer
Drug resistance mutations in response to HIV-1 protease inhibitors are selected not only in the drug target but elsewhere in the viral genome, especially at the protease cleavage sites in the precursor protein Gag. To understand the molecular basis of this protease-substrate coevolution, we solved the crystal structures of drug resistant I50V/A71V HIV-1 protease with p1-p6 substrates bearing coevolved mutations. Analyses of the protease-substrate interactions reveal that compensatory coevolved mutations in the substrate do not restore interactions lost due to protease mutations, but instead establish other interactions that are not restricted to the site of mutation. Mutation of a substrate …
Structural Analysis Of Asunaprevir Resistance In Hcv Ns3/4a Protease, Djade Soumana, Akbar Ali, Celia Schiffer
Structural Analysis Of Asunaprevir Resistance In Hcv Ns3/4a Protease, Djade Soumana, Akbar Ali, Celia Schiffer
Celia A. Schiffer
Asunaprevir (ASV), an isoquinoline-based competitive inhibitor targeting the hepatitis C virus (HCV) NS3/4A protease, is very potent in vivo. However, the potency is significantly compromised by the drug resistance mutations R155K and D168A. In this study three crystal structures of ASV and an analogue were determined to analyze the structural basis of drug resistance susceptibility. These structures revealed that ASV makes extensive contacts with Arg155 outside the substrate envelope. Arg155 in turn is stabilized by Asp168, and thus when either residue is mutated, the enzyme's interaction with ASV's P2* isoquinoline is disrupted. Adding a P1-P3 macrocycle to ASV enhances the …
A Sensitive Assay Using A Native Protein Substrate For Screening Hiv-1 Maturation Inhibitors Targeting The Protease Cleavage Site Between The Matrix And Capsid, Sook-Kyung Lee, Nancy Cheng, Emily Hull-Ryde, Marc Potempa, Celia Schiffer, William Janzen, Ronald Swanstrom
A Sensitive Assay Using A Native Protein Substrate For Screening Hiv-1 Maturation Inhibitors Targeting The Protease Cleavage Site Between The Matrix And Capsid, Sook-Kyung Lee, Nancy Cheng, Emily Hull-Ryde, Marc Potempa, Celia Schiffer, William Janzen, Ronald Swanstrom
Celia A. Schiffer
The matrix/capsid processing site in the HIV-1 Gag precursor is likely the most sensitive target to inhibit HIV-1 replication. We have previously shown that modest incomplete processing at the site leads to a complete loss of virion infectivity. In the study presented here, a sensitive assay based on fluorescence polarization that can monitor cleavage at the MA/CA site in the context of the folded protein substrate is described. The substrate, an MA/CA fusion protein, was labeled with the fluorescein-based FlAsH (fluorescein arsenical hairpin) reagent that binds to a tetracysteine motif (CCGPCC) that was introduced within the N-terminal domain of CA. …
Drug Resistance Conferred By Mutations Outside The Active Site Through Alterations In The Dynamic And Structural Ensemble Of Hiv-1 Protease, Debra Ragland, Ellen Nalivaika, Madhavi Nalam, Kristina Prachanronarong, Hong Cao, Rajintha Bandaranayake, Yufeng Cai, Nese Yilmaz, Celia Schiffer
Drug Resistance Conferred By Mutations Outside The Active Site Through Alterations In The Dynamic And Structural Ensemble Of Hiv-1 Protease, Debra Ragland, Ellen Nalivaika, Madhavi Nalam, Kristina Prachanronarong, Hong Cao, Rajintha Bandaranayake, Yufeng Cai, Nese Yilmaz, Celia Schiffer
Celia A. Schiffer
HIV-1 protease inhibitors are part of the highly active antiretroviral therapy effectively used in the treatment of HIV infection and AIDS. Darunavir (DRV) is the most potent of these inhibitors, soliciting drug resistance only when a complex combination of mutations occur both inside and outside the protease active site. With few exceptions, the role of mutations outside the active site in conferring resistance remains largely elusive. Through a series of DRV-protease complex crystal structures, inhibition assays, and molecular dynamics simulations, we find that single and double site mutations outside the active site often associated with DRV resistance alter the structure …
Testing The Substrate-Envelope Hypothesis With Designed Pairs Of Compounds, Yang Shen, Michael Altman, Akbar Ali, Madhavi Nalam, Hong Cao, Tariq Rana, Celia Schiffer, Bruce Tidor
Testing The Substrate-Envelope Hypothesis With Designed Pairs Of Compounds, Yang Shen, Michael Altman, Akbar Ali, Madhavi Nalam, Hong Cao, Tariq Rana, Celia Schiffer, Bruce Tidor
Celia A. Schiffer
Acquired resistance to therapeutic agents is a significant barrier to the development of clinically effective treatments for diseases in which evolution occurs on clinical time scales, frequently arising from target mutations. We previously reported a general strategy to design effective inhibitors for rapidly mutating enzyme targets, which we demonstrated for HIV-1 protease inhibition [Altman et al. J. Am. Chem. Soc. 2008, 130, 6099-6113]. Specifically, we developed a computational inverse design procedure with the added constraint that designed inhibitors bind entirely inside the substrate envelope, a consensus volume occupied by natural substrates. The rationale for the substrate-envelope constraint is that it …
Development Of A Novel Screening Strategy Designed To Discover A New Class Of Hiv Drugs, Nancy Cheng, Sook-Kyung Lee, P. Donover, Mel Reichman, Celia Schiffer, Emily Hull-Ryde, Ronald Swanstrom, William Janzen
Development Of A Novel Screening Strategy Designed To Discover A New Class Of Hiv Drugs, Nancy Cheng, Sook-Kyung Lee, P. Donover, Mel Reichman, Celia Schiffer, Emily Hull-Ryde, Ronald Swanstrom, William Janzen
Celia A. Schiffer
Current antiretroviral treatments target multiple pathways important for human immunodeficiency virus (HIV) multiplication, including viral entry, synthesis and integration of the DNA provirus, and the processing of viral polyprotein precursors. However, HIV is becoming increasingly resistant to these "combination therapies." Recent findings show that inhibition of HIV Gag protein cleavage into its two structural proteins, matrix (MA) and capsid (CA), has a devastating effect on viral production, revealing a potential new target class for HIV treatment. Unlike the widely used HIV protease inhibitors, this new class of inhibitor would target the substrate, not the protease enzyme itself. This approach offers …
Hiv-1 Protease-Substrate Coevolution In Nelfinavir Resistance, Madhavi Kolli, Aysegul Ozen, Nese Yilmaz, Celia Schiffer
Hiv-1 Protease-Substrate Coevolution In Nelfinavir Resistance, Madhavi Kolli, Aysegul Ozen, Nese Yilmaz, Celia Schiffer
Celia A. Schiffer
Resistance to various human immunodeficiency virus type 1 (HIV-1) protease inhibitors (PIs) challenges the effectiveness of therapies in treating HIV-1-infected individuals and AIDS patients. The virus accumulates mutations within the protease (PR) that render the PIs less potent. Occasionally, Gag sequences also coevolve with mutations at PR cleavage sites contributing to drug resistance. In this study, we investigated the structural basis of coevolution of the p1-p6 cleavage site with the nelfinavir (NFV) resistance D30N/N88D protease mutations by determining crystal structures of wild-type and NFV-resistant HIV-1 protease in complex with p1-p6 substrate peptide variants with L449F and/or S451N. Alterations of residue …
Substrate Envelope-Designed Potent Hiv-1 Protease Inhibitors To Avoid Drug Resistance, Madhavi Nalam, Akbar Ali, G. S. Kiran Kumar Reddy, Hong Cao, Saima Anjum, Michael Altman, Nese Yilmaz, Bruce Tidor, Tariq Rana, Celia Schiffer
Substrate Envelope-Designed Potent Hiv-1 Protease Inhibitors To Avoid Drug Resistance, Madhavi Nalam, Akbar Ali, G. S. Kiran Kumar Reddy, Hong Cao, Saima Anjum, Michael Altman, Nese Yilmaz, Bruce Tidor, Tariq Rana, Celia Schiffer
Celia A. Schiffer
The rapid evolution of HIV under selective drug pressure has led to multidrug resistant (MDR) strains that evade standard therapies. We designed highly potent HIV-1 protease inhibitors (PIs) using the substrate envelope model, which confines inhibitors within the consensus volume of natural substrates, providing inhibitors less susceptible to resistance because a mutation affecting such inhibitors will simultaneously affect viral substrate processing. The designed PIs share a common chemical scaffold but utilize various moieties that optimally fill the substrate envelope, as confirmed by crystal structures. The designed PIs retain robust binding to MDR protease variants and display exceptional antiviral potencies against …
Dual Recognition Of The Ribosome And The Signal Recognition Particle By The Srp Receptor During Protein Targeting To The Endoplasmic Reticulum, Elisabet C. Mandon, Ying Jiang, Reid Gilmore
Dual Recognition Of The Ribosome And The Signal Recognition Particle By The Srp Receptor During Protein Targeting To The Endoplasmic Reticulum, Elisabet C. Mandon, Ying Jiang, Reid Gilmore
Elisabet Mandon
We have analyzed the interactions between the signal recognition particle (SRP), the SRP receptor (SR), and the ribosome using GTPase assays, biosensor experiments, and ribosome binding assays. Possible mechanisms that could contribute to an enhanced affinity between the SR and the SRP-ribosome nascent chain complex to promote protein translocation under physiological ionic strength conditions have been explored. Ribosomes or 60S large ribosomal subunits activate the GTPase cycle of SRP54 and SRalpha by providing a platform for assembly of the SRP-SR complex. Biosensor experiments revealed high-affinity, saturable binding of ribosomes or large ribosomal subunits to the SR. Remarkably, the SR has …