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Publication Abstract from PubMed

The diarrheal pathogen Vibrio cholerae navigates complex environments using three chemosensory systems and 44-45 chemoreceptors. Chemosensory cluster II modulates chemotaxis, whereas clusters I and III have unknown functions. Ligands have been identified for only five V. cholerae chemoreceptors. Here we report that the cluster III receptor, VcAer2, binds and responds to O2 . VcAer2 is an ortholog of Pseudomonas aeruginosa Aer2 (PaAer2), but differs in that VcAer2 has two, rather than one, N-terminal PAS domain. We have determined that both PAS1 and PAS2 form homodimers and bind penta-coordinate b-type heme via an Eeta-His residue. Heme binding to PAS1 required the entire PAS core, but receptor function also required the N-terminal cap. PAS2 functioned as an O2 -sensor [Kd(O2) , 19 muM], utilizing the same Ibeta Trp (W276) as PaAer2 to stabilize O2 . The crystal structure of PAS2-W276L was similar to that of PaAer2-PAS, but resided in an active conformation mimicking the ligand-bound state, consistent with its signal-on phenotype. PAS1 also bound O2 [Kd(O2), 12 muM], although O2 binding was stabilized by either a Trp or Tyr residue. Moreover, PAS1 appeared to function as a signal modulator, regulating O2 -mediated signaling from PAS2, and resulting in activation of the cluster III chemosensory pathway. This article is protected by copyright. All rights reserved.

THE AER2 RECEPTOR FROM VIBRIO CHOLERAE IS A DUAL PAS-HEME OXYGEN SENSOR.,Greer-Phillips SE, Sukomon N, Chua TK, Johnson MS, Crane BR, Watts KJ Mol Microbiol. 2018 May 2. doi: 10.1111/mmi.13978. PMID:29719085^[1]

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