Cystathionine β-synthase (CBS) domains 1 and 2 fulfill different roles in ionic strength sensing of the ATP-binding cassette (ABC) transporter OpuA.

ABSTRACT: The cystathionine β-synthase module of OpuA in conjunction with an anionic membrane surface acts as a sensor of internal ionic strength, which allows the protein to respond to osmotic stress. We now show by chemical modification and cross-linking studies that CBS2-CBS2 interface residues are critical for transport activity and/or ionic regulation of transport, whereas CBS1 serves no functional role. We establish that Cys residues in CBS1, CBS2, and the nucleotide-binding domain are more accessible for cross-linking at high than low ionic strength, indicating that these domains undergo conformational changes when transiting between the active and inactive state. Structural analyses suggest that the cystathionine β-synthase module is largely unstructured. Moreover, we could substitute CBS1 b

SUBMITTER: Karasawa A 

PROVIDER: S-EPMC3199475 | biostudies-literature | 2011 Oct

REPOSITORIES: biostudies-literature