Sensor kinase/response regulator system

In addition to kinase-phosphatase cycles, bacteria use at least two other ATP-dependent regulatory mechanisms." In the sensor kinase/response regulator (or "two-component") systems" " a sensor protein, upon being allosterically activated, phosphorylates itself (autophosphorylation) on a specific histidyl residue to form an N-phosphohistidine derivative. 

They are usually synthesized as small precursor proteins or peptides that are processed with proteolytic elimination of their Af-terminal leader sequences, and the resultant mature peptides form one, two, or more putative amphipathic transmembrane a-helical spanners (TMSs). Many bacteriocins are encoded in operons that also encode an immunity protein and an ABC transport system (TC 3.A.l) with a protease domain at the Af-terminus. The ABC systems export the bacteriocins while the protease domains cleave the A-terminal leader sequence. A few bacteriocins are exported by the type II general secretory pathway rather than by ABC-type export systems. In some cases, expression of the bacteriocin-encoding operon is induced by a bacteriocin-like peptide which acts in conjunction with a two component sensor kinase-response regulator. 

Colby, P. Davies, S. Kelly, D.J. Cuest, J.R. Andrews, S.C. Identification and characterization of a two-component sensor-kinase and response-regulator system (DcuS-DcuR) controlling gene expression in response to C4-dicarboxylates in Escherichia coli. J. BacterioL, 181, 1238-1248 (1999)... 

HambUn, M.J. Shaw, J.C. Kelly, D.J. Sequence analysis and interposon mutagenesis of a sensor-kinase (DctS) and response-regulator (DctR) controlling synthesis of the high-affinity C4-dicarboxylate transport system in Rhodobacter capsulatus. Mol. Cen. Cenet., 237, 215-224 (1993)... 

This system is employed by prokaryotic organisms, and homologous pathways have recently been identified in eukaryotes. The prototypical two-component pathway consists of two proteins A protein histidine kinase (sensor kinase) and a response regulator. Histidine kinases are very distinct from the superfamily of conventional protein serine/threonine and tyrosine kinases. The histidine kinases auto-phosphorylate on histidine residues and are involved in the phosphorylation of aspartate amino acids and their targets. 

In two-component systems in bacteria (Fig. 4), signal perception by the A -terminal domain of the sensor (which is usually located in the periplasmic space flanked by two or more transmembrane domains) results in autophosphorylation of a carboxyl-terminal histidine kinase domain, the phosphate group is then transferred to an aspartate residue in the A -terminal of the receiver domain of the response regulator which in turn via the output domain regulates its activity - for example as a transcriptional activator [42]. 

CheA is a histidine kinase that belongs to the superfamily of two-component regulatory systems, each constituting a sensor (a histidine kinase) and a response regulator [573], As mentioned above, CheA together with CheW and the MCPs forms a ternary complex at the bacterial poles [256, 463, 635],... 

The genome of Streptomyces species is very large (from 8 to 10.5 Mb). Sixty-seven paired two component systems (TCS), 13 orphan response regulators and 17 unpaired sensor kinases have been identified in the genome of S. coelicolor... 

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