Protein Structure

蛋白质结构

• 批准号: 6763645
• 负责人: ALEX WLODAWER
• 金额: --
• 依托单位: DIVISION OF BASIC SCIENCES - NCI
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/6763645
• 关键词: X ray crystallography; antineoplastics; asparaginase; drug resistance; drug screening /evaluation; endopeptidases; endoribonucleases; enzyme complex; enzyme inhibitors; equine infectious anemia virus; feline immunodeficiency virus; human immunodeficiency virus 1; lymphocytic leukemia; monocyte chemoattractant protein 1; mutant; pharmacokinetics; protein structure function

We are studying the relationship between protein structure and function, using the technique of high-resolution X-ray diffraction. In the past year, our work has been concentrated in four distinct areas. Enzymes with Anticancer Properties We have been investigating the crystal structures of several members of the family of L-asparaginases, some of which are used clinically as drugs directed against childhood lymphoblastic leukemia. While the mechanism of anticancer activity of these enzymes is not yet clear, we have concentrated on the studies of their enzymatic properties. Investigations of the T12V and T89V mutants of Escherichia coli L-asparaginase resulted in the discovery of a covalent intermediate in the active site of the latter variant, leading to the postulate that T12 might be directly involved as a nucleophile in the first step of catalysis. Several other mutants were also crystallized. We have also studied these enzymes complexed with ligands such as glutamate and succinic acid, and we determined the structure of a related protein from Wolinella succinogenes. Another enzyme with potential therapeutic properties is Onconase, a cytotoxic ribonuclease isolated from frog eggs. We have been involved in reengineering this enzyme in order to make it applicable to human cancer therapy and to restore its activity in the absence of posttranslational modifications. We also solved at atomic resolution the crystal structure of eosinofil-derived neurotoxin (EDN), a related enzyme now being developed as a potential anti-cancer agent. Cytokines and Cytokine Receptors Our section has been investigating the crystal structures of several cytokines and has made progress in preparing their receptor complexes. We have established that a helical cytokine, interleukin-10 (IL-10), is a domain-swapped dimer in which each compact half is composed of fragments of two identical molecules. The structure of a related cytokine encoded in the genome of Epstein-Barr virus has now been determined, providing the first glimpse of the molecular architecture of an agent used by the virus to control the host's immune system. We have recently solved the crystal structure of IL-19, a novel chemokine related to IL-10, and are attempting to crystallize its complexes with specific receptors. Retroviral Enzymes Enzymes encoded by retroviruses such as HIV are prime targets for designing effective drug therapies. We have been studying the structure of native and drug-resistant HIV-1 protease (PR) complexed with inhibitors, with the aim of tracing the molecular basis of the resistance phenomenon. We have also determined the structures of related enzymes from feline immunodeficiency virus (FIV) and equine infectious anemia virus (EIAV). The latter PRs are poorly inhibited by most inhibitors of HIV-1 PR, including those in clinical use, although they are capable of cleaving HIV-1-derived sequences. To study the mechanism of drug resistance, we solved the structures of HIV-1, FIV, and EIAV PRs complexed with an identical inhibitor, while the studies of an inactive mutant of FIV PR with a substrate helped in delineating the catalytic mechanism. Another retroviral enzyme under investigation in our laboratory is integrase. We have solved the structure of the catalytic domain of avian sarcoma virus integrase in the presence and absence of divalent cations to atomic resolution, and are attempting cocrystallization of complexes with different substrates. Proteins with antiviral properties We solved the crystal structure of cyanovirin-N, a protein that prevents binding of HIV to its cellular receptor. Since this is accomplished through interactions with high-mannose sugars, we also solved the structure of two such specific complexes, elucidating the mode of binding. We also obtained crystals of another protein with similar properties, scytovirin.

我们正在利用高分辨率x射线衍射技术研究蛋白质结构与功能之间的关系。一年来，我们的工作主要集中在四个方面。