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Probing the nucleotide binding and phosphorylation by the histidine kinase of a novel three‐protein two‐component system from Mycobacterium tuberculosis
Author(s) -
Shrivastava Rashmi,
Ghosh Ananta Kumar,
Das Amit Kumar
Publication year - 2007
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2007.03.089
Subject(s) - mycobacterium tuberculosis , two component regulatory system , histidine kinase , histidine , component (thermodynamics) , phosphorylation , nucleotide , chemistry , kinase , biochemistry , tuberculosis , biology , microbiology and biotechnology , medicine , enzyme , gene , mutant , physics , pathology , thermodynamics
The two‐component signal transduction system from Mycobacterium tuberculosis bears a unique three‐protein system comprising of two putative histidine kinases (HK1 and HK2) and one response regulator TcrA. By sequence analysis, HK1 is found to be an adenosine 5′‐triphosphate (ATP) binding protein, similar to the nucleotide‐binding domain of homologous histidine kinases, and HK2 is a unique histidine containing phosphotransfer (HPt)‐mono‐domain protein. HK1 is expected to interact with and phosphorylate HK2. Here, we show that HK1 binds 2′(3′)‐ O ‐(2,4,6‐trinitrophenyl)adenosine 5′‐triphosphate monolithium trisodium salt and ATP with a 1:1 stoichiometric ratio. The ATPase activity of HK1 in the presence of HK2 was measured, and phosphorylation experiments suggested that HK1 acts as a functional kinase and phosphorylates HK2 by interacting with it. Further phosphorylation studies showed transfer of a phosphoryl group from HK2 to the response regulator TcrA. These results indicate a new mode of interaction for phosphotransfer between the two‐component system proteins in bacteria.