title: Crystal structure of the Mycobacterium tuberculosis phosphate binding protein PstS3.
abstract: Mycobacterium tuberculosis evades host immune responses by colonizing macrophages. Intraphagosomal M. tuberculosis is exposed to environmental stresses such as reactive oxygen and nitrogen intermediates as well as acid shock and inorganic phosphate (Pi) depletion. Experimental evidence suggests that expression levels of mycobacterial protein PstS3 (Rv0928) are significantly increased when M. tuberculosis bacilli are exposed to Pi starvation. Hence, PstS3 may be important for survival of Mtb in conditions where there is limited supply of Pi. We report here the structure of PstS3 from M. tuberculosis at 2.3-Å resolution. The protein presents a structure typical for ABC phosphate transfer receptors. Comparison with its cognate receptor PstS1 showed a different pattern distribution of surface charges in proximity to the Pi recognition site, suggesting complementary roles of the two proteins in Pi uptake.
authors.affiliation: Department of Pharmaceutical Sciences, Università del Piemonte Orientale "A. Avogadro,", Largo Donegani 2, 28100, Novara, Italy.
authors.forename: Davide M
authors.initials: DM
authors.lastname: Ferraris
authors.forename: Ralf
authors.initials: R
authors.lastname: Spallek
authors.forename: Wulf
authors.initials: W
authors.lastname: Oehlmann
authors.forename: Mahavir
authors.initials: M
authors.lastname: Singh
authors.forename: Menico
authors.initials: M
authors.lastname: Rizzi
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000096:biosynthesis / Q000648:ultrastructure*; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000648:ultrastructure*; D018360:Crystallography, X-Ray; D015964:Gene Expression Regulation, Bacterial; D008264:Macrophages / Q000276:immunology; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009169:Mycobacterium tuberculosis / Q000276:immunology*; D028044:Phosphate-Binding Proteins / Q000648:ultrastructure*; D010710:Phosphates / Q000378:metabolism*; D011485:Protein Binding; D058849:Protein Refolding; D016415:Sequence Alignment
chemical_list: D018528:ATP-Binding Cassette Transporters; D001426:Bacterial Proteins; D028044:Phosphate-Binding Proteins; D010710:Phosphates; C102010:PstS-3 protein, Mycobacterium tuberculosis
keywords: Pst system; bacterial survival; binding affinity; phosphate depletion; protein refolding and crystallization; thermal shift assay; tuberculosis; two-component system