4cxf
Structure of CnrH in complex with the cytosolic domain of CnrY
Structural highlights
FunctionCNRH_CUPMC Sigma factors are initiation factors that promote the attachment of RNA polymerase to specific initiation sites and are then released. This sigma factor regulates the genes for a membrane-located efflux system that confers resistance to nickel and cobalt. CnrH alone is able to activate CNR expression, while both CnrY and CrnX are needed for nickel induction of cnrH (PubMed:10671463). Binds DNA in an RNA polymerase-dependent fashion (PubMed:10671464). CnrH may be controlled by a CnrYX transmembrane anti-sigma factor complex which binds CnrH in the absence of Ni(2+). If Ni(2+) appears in the periplasm, it may be bound by CnrR (CnrX); the signal then would be transmitted by CnrY into the cytoplasm and CnrH would be released.[1] [2] Publication Abstract from PubMedGene expression in bacteria is regulated at the level of transcription initiation, a process driven by sigma factors. The regulation of sigma factor activity proceeds from the regulation of their cytoplasmic availability, which relies on specific inhibitory proteins called anti-sigma factors. With anti-sigma factors regulating their availability according to diverse cues, extracytoplasmic function sigma factors (sigmaECF) form a major signal transduction system in bacteria. Here, structure:function relationships have been characterized in an emerging class of minimal-size transmembrane anti-sigma factors, using CnrY from Cupriavidus metallidurans CH34 as a model. This study reports the 1.75-A-resolution structure of CnrY cytosolic domain in complex with CnrH, its cognate sigmaECF, and identifies a small hydrophobic knob in CnrY as the major determinant of this interaction in vivo. Unsuspected structural similarity with the molecular switch regulating the general stress response in alpha-proteobacteria unravels a new class of anti-sigma factors targeting sigmaECF. Members of this class carry out their function via a 30-residue stretch that displays helical propensity but no canonical structure on its own. The Crystal Structure of the Anti-sigma Factor CnrY in Complex with the sigma Factor CnrH Shows a New Structural Class of Anti-sigma Factors Targeting Extracytoplasmic Function sigma Factors.,Maillard AP, Girard E, Ziani W, Petit-Hartlein I, Kahn R, Coves J J Mol Biol. 2014 Apr 12. pii: S0022-2836(14)00177-6. doi:, 10.1016/j.jmb.2014.04.003. PMID:24727125[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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