Domain Structure of Virulence-associated Response Regulator PhoP of Mycobacterium tuberculosis: ROLE OF THE LINKER REGION IN REGULATOR-PROMOTER INTERACTION(S)

• Published in: The Journal of biological chemistry Vol. 285; no. 45; pp. 34309 - 34318
• Main Authors: Pathak, Anuj, Goyal, Rajni, Sinha, Akesh, Sarkar, Dibyendu
• Format: Journal Article
• Language: English
• Published: United States American Society for Biochemistry and Molecular Biology 05.11.2010
• Subjects: Bacterial Proteins - chemistry; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; DNA, Bacterial - chemistry; DNA, Bacterial - genetics; DNA, Bacterial - metabolism; DNA-Binding Proteins - chemistry; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; Gene Regulation; Lipids - biosynthesis; Lipids - genetics; Mycobacterium tuberculosis; Mycobacterium tuberculosis - chemistry; Mycobacterium tuberculosis - genetics; Mycobacterium tuberculosis - metabolism; Mycobacterium tuberculosis - pathogenicity; Phosphorylation; Promoter Regions, Genetic; Protein Binding; Protein Structure, Tertiary; Virulence Factors - chemistry; Virulence Factors - genetics; Virulence Factors - metabolism
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M110.135822

The PhoP and PhoR proteins from Mycobacterium tuberculosis form a highly specific two-component system that controls expression of genes involved in complex lipid biosynthesis and regulation of unknown virulence determinants. The several functions of PhoP are apportioned between a C-terminal effector domain (PhoPC) and an N-terminal receiver domain (PhoPN), phosphorylation of which regulates activation of the effector domain. Here we show that PhoPN, on its own, demonstrates PhoR-dependent phosphorylation. PhoPC, the truncated variant bearing the DNA binding domain, binds in vitro to the target site with affinity similar to that of the full-length protein. To complement the finding that residues spanning Met¹ to Arg¹³⁸ of PhoP constitute the minimal functional PhoPN, we identified Arg¹⁵⁰ as the first residue of the distal PhoPC domain capable of DNA binding on its own, thereby identifying an interdomain linker. However, coupling of two functional domains together in a single polypeptide chain is essential for phosphorylation-coupled DNA binding by PhoP. We discuss consequences of tethering of two domains on DNA binding and demonstrate that linker length and not individual residues of the newly identified linker plays a critical role in regulating interdomain interactions. Together, these results have implications for the molecular mechanism of transmission of conformation change associated with phosphorylation of PhoP that results in the altered DNA recognition by the C-terminal domain.