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Articles 1 - 6 of 6
Full-Text Articles in Microbiology
Defining Electron Bifurcation In The Electron-Transferring Flavoprotein Family, Amaya M. Garcia Costas, Saroj Poudel, Anne-Frances Miller, Gerrit J. Schut, Rhesa N. Ledbetter, Kathryn R. Fixen, Lance C. Seefeldt, Michael W. W. Adams, Caroline S. Harwood, Eric S. Boyd, John W. Peters
Defining Electron Bifurcation In The Electron-Transferring Flavoprotein Family, Amaya M. Garcia Costas, Saroj Poudel, Anne-Frances Miller, Gerrit J. Schut, Rhesa N. Ledbetter, Kathryn R. Fixen, Lance C. Seefeldt, Michael W. W. Adams, Caroline S. Harwood, Eric S. Boyd, John W. Peters
Chemistry Faculty Publications
Electron bifurcation is the coupling of exergonic and endergonic redox reactions to simultaneously generate (or utilize) low- and high-potential electrons. It is the third recognized form of energy conservation in biology and was recently described for select electron-transferring flavoproteins (Etfs). Etfs are flavin-containing heterodimers best known for donating electrons derived from fatty acid and amino acid oxidation to an electron transfer respiratory chain via Etf-quinone oxidoreductase. Canonical examples contain a flavin adenine dinucleotide (FAD) that is involved in electron transfer, as well as a non-redox-active AMP. However, Etfs demonstrated to bifurcate electrons contain a second FAD in place of the …
Structural And Thermodynamic Basis Of Amprenavir/Darunavir And Atazanavir Resistance In Hiv-1 Protease With Mutations At Residue 50, Seema Mittal, Rajintha Bandaranayake, Nancy King, Moses Prabu-Jeyabalan, Madhavi Nalam, Ellen Nalivaika, Nese Yilmaz, Celia Schiffer
Structural And Thermodynamic Basis Of Amprenavir/Darunavir And Atazanavir Resistance In Hiv-1 Protease With Mutations At Residue 50, Seema Mittal, Rajintha Bandaranayake, Nancy King, Moses Prabu-Jeyabalan, Madhavi Nalam, Ellen Nalivaika, Nese Yilmaz, Celia Schiffer
Celia A. Schiffer
Drug resistance occurs through a series of subtle changes that maintain substrate recognition but no longer permit inhibitor binding. In HIV-1 protease, mutations at I50 are associated with such subtle changes that confer differential resistance to specific inhibitors. Residue I50 is located at the protease flap tips, closing the active site upon ligand binding. Under selective drug pressure, I50V/L substitutions emerge in patients, compromising drug susceptibility and leading to treatment failure. The I50V substitution is often associated with amprenavir (APV) and darunavir (DRV) resistance, while the I50L substitution is observed in patients failing atazanavir (ATV) therapy. To explain how APV, …
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 …
Molecular Mechanisms Of Viral And Host Cell Substrate Recognition By Hepatitis C Virus Ns3/4a Protease, Keith Romano, Jennifer Laine, Laura Deveau, Hong Cao, Francesca Massi, Celia Schiffer
Molecular Mechanisms Of Viral And Host Cell Substrate Recognition By Hepatitis C Virus Ns3/4a Protease, Keith Romano, Jennifer Laine, Laura Deveau, Hong Cao, Francesca Massi, Celia Schiffer
Celia A. Schiffer
Hepatitis C NS3/4A protease is a prime therapeutic target that is responsible for cleaving the viral polyprotein at junctions 3-4A, 4A4B, 4B5A, and 5A5B and two host cell adaptor proteins of the innate immune response, TRIF and MAVS. In this study, NS3/4A crystal structures of both host cell cleavage sites were determined and compared to the crystal structures of viral substrates. Two distinct protease conformations were observed and correlated with substrate specificity: (i) 3-4A, 4A4B, 5A5B, and MAVS, which are processed more efficiently by the protease, form extensive electrostatic networks when in complex with the protease, and (ii) TRIF and …
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 …
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 …