2awc

Publication Abstract from PubMed

The methyl-accepting chemotaxis protein, DcrH, from the anaerobic sulfate-reducing bacterium, Desulfovibrio vulgaris (Hildenborough), has a hemerythrin-like domain, DcrH-Hr, at its C terminus. DcrH-Hr was previously shown to contain a diiron site that binds O2, suggesting an O2-sensing function. X-ray crystal structures of diferric (met-), azido-diferric (azidomet-), and diferrous (deoxy-) DcrH-Hr reveal a "substrate tunnel" distinct from that in invertebrate hemerythrins. This tunnel is proposed to facilitate the rapid autoxidation of oxy-DcrH-Hr and suggests that sensing is triggered by O2 binding and subsequent oxidation of the diferrous active site. The N-terminal loop of DcrH-Hr is highly ordered in both met- and azidomet-DcrH-Hr but is disordered in deoxy-DcrH-Hr. These redox-dependent conformational differences presumably transduce the sensory signal of DcrH-Hr to the neighboring methylation domain in the full-length receptor. Given the putative cytoplasmic localization of its Hr-like O2-sensing domain, DcrH is proposed to serve a role in negative aerotaxis (anaerotaxis).

Structural basis for O2 sensing by the hemerythrin-like domain of a bacterial chemotaxis protein: substrate tunnel and fluxional N terminus.,Isaza CE, Silaghi-Dumitrescu R, Iyer RB, Kurtz DM Jr, Chan MK Biochemistry. 2006 Aug 1;45(30):9023-31. PMID:16866347^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.