Structural Studies of the Anti-HIV Human Protein APOBEC3G Catalytic Domain: A Dissertation
Authors
Shandilya, ShivenderFaculty Advisor
Celia A. Schiffer, Ph.D.Academic Program
Biochemistry and Molecular PharmacologyUMass Chan Affiliations
Biochemistry and Molecular PharmacologyDocument Type
Doctoral DissertationPublication Date
2011-08-12Keywords
Cytidine DeaminaseCatalytic Domain
HIV Infections
HIV-1
Biochemistry, Biophysics, and Structural Biology
Enzymes and Coenzymes
Genetic Phenomena
Immune System Diseases
Pharmaceutical Preparations
Therapeutics
Virology
Virus Diseases
Viruses
Metadata
Show full item recordAbstract
HIV/AIDS is a disease of grave global importance with over 33 million people infected world-wide and nearly 2 million deaths each year. The rapid emergence of drug resistance, due to viral mutation, renders anti-retroviral drug candidates ineffective with alarming speed and regularity. Instead of targeting mutation prone viral proteins, an alternative approach is to target host proteins that interact with viral proteins and are critical for the HIV life-cycle. APOBEC3G is a host anti-HIV restriction factor that can exert tremendous negative pressure by hypermutating the viral genome and has the potential to be a promising candidate for anti-retroviral therapeutic research. The work presented in this thesis is focused on investigating the A3G catalytic domain structure and implications of various observed structural features for biological function. High-resolution crystal structures of the A3G catalytic domain were solved using data from macromolecular X-ray crystallographic experiments, revealing a novel intermolecular zinc coordinating motif unique to A3G. Major intermolecular interfaces observed in the crystal structure were investigated for relevance to biochemical activity and biological function. Co-crystallization with a small-molecule A3G inhibitor, discovered using high-throughput screening assays, revealed a cysteine residue near the active site that is critical for inhibition of catalytic activity by catechol moieties. The serendipitous discovery of covalent interactions between this inhibitor and a surface cysteine residue led to further biochemical experiments that revealed the other cysteine, near the active site, to be critical for inhibition. Computational modeling was used to propose a steric-hinderance based mechanism of action that was supported by mutational experiments. Structures of other human APOBEC3 homologs were modeled using in-silico methods examined for similarities and differences with A3G catalytic domain crystal structures. Comparisons based on these homology models suggest putative structural features that may endow substrate specificity and other characteristics to the APOBEC3 family members.DOI
10.13028/g37q-6j42Permanent Link to this Item
http://hdl.handle.net/20.500.14038/31904Rights
Copyright is held by the author, with all rights reserved.ae974a485f413a2113503eed53cd6c53
10.13028/g37q-6j42