Probing the nucleotide binding and phosphorylation by the histidine kinase of a novel three-protein two-component system from Mycobacterium tuberculosis.
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.
Shrivastava
Rashmi
R
Department of Biotechnology, Indian Institute of Technology-Kharagpur, Kharagpur 721 302, India.
Ghosh
Ananta Kumar
AK
Das
Amit Kumar
AK
D000251:Adenosine Triphosphatases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism; D000071677:Histidine Kinase; D008969:Molecular Sequence Data; D046912:Multiprotein Complexes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D009169:Mycobacterium tuberculosis / Q000201:enzymology* / Q000235:genetics; D010766:Phosphorylation; D011485:Protein Binding; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D046912:Multiprotein Complexes; D000255:Adenosine Triphosphate; D011494:Protein Kinases; D000071677:Histidine Kinase; D000251:Adenosine Triphosphatases