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Publication Abstract from PubMed

The PhoP protein from Mycobacterium tuberculosis is a response regulator of the OmpR/PhoB subfamily, whose structure consists of an N-terminal receiver domain and a C-terminal DNA-binding domain. How the DNA-binding activities are regulated by phosphorylation of the receiver domain remains unclear due to a lack of structural information on the full-length proteins. Here we report the crystal structure of the full-length PhoP of M. tuberculosis. Unlike other known structures of full-length proteins of the same subfamily, PhoP forms a dimer through its receiver domain with the dimer interface involving alpha4-beta5-alpha5, a common interface for activated receiver domain dimers. However, the switch residues, Thr99 and Tyr118, are in a conformation resembling those of nonactivated receiver domains. The Tyr118 side chain is involved in the dimer interface interactions. The receiver domain is tethered to the DNA-binding domain through a flexible linker and does not impose structural constraints on the DNA-binding domain. This structure suggests that phosphorylation likely facilitates/stabilizes receiver domain dimerization, bringing the DNA-binding domains to close proximity, thereby increasing their binding affinity for direct repeat DNA sequences.

Structure of the Response Regulator PhoP from Mycobacterium tuberculosis Reveals a Dimer through the Receiver Domain.,Menon S, Wang S Biochemistry. 2011 Jul 5;50(26):5948-57. Epub 2011 Jun 13. PMID:21634789^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.