title: The nitric oxide-responsive regulator NsrR controls ResDE-dependent gene expression.
abstract: The ResD-ResE signal transduction system is essential for aerobic and anaerobic respiration in Bacillus subtilis. ResDE-dependent gene expression is induced by oxygen limitation, but full induction under anaerobic conditions requires nitrite or nitric oxide (NO). Here we report that NsrR (formerly YhdE) is responsible for the NO-dependent up-regulation of the ResDE regulon. The null mutation of nsrR led to aerobic derepression of hmp (flavohemoglobin gene) partly in a ResDE-independent manner. In addition to its negative role in aerobic hmp expression, NsrR plays an important role under anaerobic conditions for regulation of ResDE-controlled genes, including hmp. ResDE-dependent gene expression was increased by the nsrR mutation in the absence of NO, but the expression was decreased by the mutation when NO was present. Consequently, B. subtilis cells lacking NsrR no longer sense and respond to NO (and nitrite) to up-regulate the ResDE regulon. Exposure to NO did not significantly change the cellular concentration of NsrR, suggesting that NO likely modulates the activity of NsrR. NsrR is similar to the recently described nitrite- or NO-sensitive transcription repressors present in various bacteria. NsrR likely has an Fe-S cluster, and interaction of NO with the Fe-S center is proposed to modulate NsrR activity.
authors.affiliation: Department of Environmental and Biomolecular Systems, OGI School of Science and Engineering, Oregon Health and Science University, 20000 NW Walker Road, Beaverton, OR 97006, USA. mnakano@ebs.ogi.edu
authors.forename: Michiko M
authors.initials: MM
authors.lastname: Nakano
authors.forename: Hao
authors.initials: H
authors.lastname: Geng
authors.forename: Shunji
authors.initials: S
authors.lastname: Nakano
authors.forename: Kazuo
authors.initials: K
authors.lastname: Kobayashi
mesh_terms: D000332:Aerobiosis; D001412:Bacillus subtilis / Q000187:drug effects / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D009154:Mutation; D009569:Nitric Oxide / Q000494:pharmacology*; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic; D015854:Up-Regulation
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D014157:Transcription Factors; D009569:Nitric Oxide