Structural highlights
Function
[CHER_BACSU] Methylation of the membrane-bound methyl-accepting chemotaxis proteins (MCP) to form gamma-glutamyl methyl ester residues in MCP. CheR is responsible for the chemotactic adaptation to repellents.
Publication Abstract from PubMed
Chemotactic methyltransferase, CheR catalyse methylation of specific glutamate residues in the cytoplasmic domain of methyl-accepting chemotactic protein receptors (MCPRs). The methylation of MCPRs is essential for the chemical sensing and chemotactic bacterial mobility towards favorable chemicals or away from unfavorable ones. In this study, crystal structure of B. subtilis CheR (BsCheR) in complex with S-adenosyl-l-homocysteine (SAH) has been determined to 1.8A resolution. This is the first report of crystal structure belonging to the pentapeptide-independent CheR (PICheR) class. Till date, only one crystal structure of CheR from S. typhimurium (StCheR) belonging to pentapeptide-dependent CheR (PDCheR) class is available. Structural analysis of BsCheR reveals a helix-X-helix motif (HXH) with Asp53 as the linker residue in the N-terminal domain. The key structural features of the PDCheR beta-subdomain involved in the formation of a tight complex with the pentapeptide binding motif in MCPRs were found to be absent in the structure of BsCheR. Additionally, isothermal titration calorimetry (ITC) experiments were performed to investigate S-adenosyl-(l)-methionine (SAM) binding affinity and KD was determined to be 0.32mM. The structure of BsCheR reveals that mostly residues of the large C-terminal domain contribute to SAH binding, with contributions of few residues from the linker region and the N-terminal domain. Structural investigations and sequence analysis carried out in this study provide critical insights into the distinct receptor recognition mechanism of the PDCheR and PICheR methyltransferase classes.
Crystal structure of pentapeptide-independent chemotaxis receptor methyltransferase (CheR) reveals idiosyncratic structural determinants for receptor recognition.,Batra M, Sharma R, Malik A, Dhindwal S, Kumar P, Tomar S J Struct Biol. 2016 Aug 17. pii: S1047-8477(16)30174-5. doi:, 10.1016/j.jsb.2016.08.005. PMID:27544050[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Batra M, Sharma R, Malik A, Dhindwal S, Kumar P, Tomar S. Crystal structure of pentapeptide-independent chemotaxis receptor methyltransferase (CheR) reveals idiosyncratic structural determinants for receptor recognition. J Struct Biol. 2016 Aug 17. pii: S1047-8477(16)30174-5. doi:, 10.1016/j.jsb.2016.08.005. PMID:27544050 doi:http://dx.doi.org/10.1016/j.jsb.2016.08.005
