Structural studies of ATP phosphoribosyltransferase from Mycobacterium tuberculosis and virtual screening for its novel inhibitors : a dissertation /
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| Format: | Thesis Book |
| Language: | English |
| Published: |
[College Station, Tex.] :
[Texas A&M University System Health Science Center],
[2005]
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| Subjects: |
| Abstract: | ABSTRACT: N-1-(5-phosphoribosyl)-ATP transferase (ATP-PRTase/HisG) of Mycobacterium tuberculosis (M. tuberculosis) was cloned from genomic DNA with a 6-His tag at the N-terminus and overexpressed and crystallized in the presence or absence of the natural inhibitors, AMp and histidine in different conditions respectively. The crystal structures of ATp-PRTase were solved from electron density maps calculated by multiple-wavelength anomalous diffraction (MAD) methods. The structure has three distinct domains (I, II and III). The active site is formed between the domain I and II, which is widely exposed to solvent. A large conformational change is induced by histidine binding on domain III. This allosteric inhibition mechanism seems to limit substrate accessibility to the active site by inducing a "closed" conformation of the inactive hexameric enzyme. In addition, this mechanism allows additional inter-subunit interactions to AMP, which is bound far from the histidine-binding site. This explains syngergistic inhibition between the natural inhibitors and is consistent with previous biochemical evidences (Morton and Parsons 1977) that demonstrated enhanced inhibition in the presence of the both inhibitors. Screening were tested in vivo against Mycobacterium smegmatis (M. smegmatis), a surrogate marker of M. tuberculosis. Two of them revealed inhibition of the bacterial growth. In particular, Chembridge compound 5341947 showed 100% inhibition at 25 ug/ml. |
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| Item Description: | Vita. "Major Subject: Medical Sciences". "Submitted to the Graduate School of Biomedical Sciences of The Texas A&M University System Health Science Center in partial fulfillment for the requirements for the degree of Doctor of Philosophy May 2005." Approved as to style and content by: James C. Sacchettini, Wallace L. McKeehan, Frederick S. Gimble, Jerry Tsai, Richard H. Finnell. |
| Physical Description: | xi, 207 leaves : illustrations ; 28 cm. |
| Bibliography: | Includes bibliographical references (leaves 182-206). |