Format

Send to

Choose Destination
J Mol Biol. 2012 Jan 27;415(4):759-67. doi: 10.1016/j.jmb.2011.11.043. Epub 2011 Dec 6.

The receptor-CheW binding interface in bacterial chemotaxis.

Author information

1
Department of Chemistry and Biochemistry, University ofCalifornia Santa Barbara, Santa Barbara, CA93106-9510, USA.

Abstract

The basic structural unit of the signaling complex in bacterial chemotaxis consists of the chemotaxis kinase CheA, the coupling protein CheW, and chemoreceptors. These complexes play an important role in regulating the kinase activity of CheA and in turn controlling the rotational bias of the flagellar motor. Although individual three-dimensional structures of CheA, CheW, and chemoreceptors have been determined, the interaction between chemoreceptor and CheW is still unclear. We used nuclear magnetic resonance to characterize the interaction modes of chemoreceptor and CheW from Thermotoga maritima. We find that chemoreceptor binding surface is located near the highly conserved tip region of the N-terminal helix of the receptor, whereas the binding interface of CheW is placed between the β-strand 8 of domain 1 and the β-strands 1 and 3 of domain 2. The receptor-CheW complex shares a similar binding interface to that found in the "trimer-of-dimers" oligomer interface seen in the crystal structure of cytoplasmic domains of chemoreceptors from Escherichia coli. Based on the association constants inferred from fast exchange chemical shifts associated with receptor-CheW titrations, we estimate that CheW binds about four times tighter to its first binding site of the receptor dimer than to its second binding site. This apparent anticooperativity in binding may reflect the close proximity of the two CheW binding surfaces near the receptor tip or further, complicating the events at this highly conserved region of the receptor. This work describes the first direct observation of the interaction between chemoreceptor and CheW.

PMID:
22155081
PMCID:
PMC3279196
DOI:
10.1016/j.jmb.2011.11.043
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Elsevier Science Icon for PubMed Central
Loading ...
Support Center