title: Respiration control of multicellularity in Bacillus subtilis by a complex of the cytochrome chain with a membrane-embedded histidine kinase.
abstract: Bacillus subtilis forms organized multicellular communities known as biofilms wherein the individual cells are held together by a self-produced extracellular matrix. The environmental signals that promote matrix synthesis remain largely unknown. We discovered that one such signal is impaired respiration. Specifically, high oxygen levels suppressed synthesis of the extracellular matrix. In contrast, low oxygen levels, in the absence of an alternative electron acceptor, led to increased matrix production. The response to impaired respiration was blocked in a mutant lacking cytochromes caa3 and bc and markedly reduced in a mutant lacking kinase KinB. Mass spectrometry of proteins associated with KinB showed that the kinase was in a complex with multiple components of the aerobic respiratory chain. We propose that KinB is activated via a redox switch involving interaction of its second transmembrane segment with one or more cytochromes under conditions of reduced electron transport. In addition, a second kinase (KinA) contributes to the response to impaired respiration. Evidence suggests that KinA is activated by a decrease in the nicotinamide adenine dinucleotide (NAD(+))/NADH ratio via binding of NAD(+) to the kinase in a PAS domain A-dependent manner. Thus, B. subtilis switches from a unicellular to a multicellular state by two pathways that independently respond to conditions of impaired respiration.
authors.affiliation: The Biological Laboratories, Harvard University, Cambridge, Massachusetts 02138, USA.
authors.forename: Ilana
authors.initials: I
authors.lastname: Kolodkin-Gal
authors.forename: Alexander K W
authors.initials: AK
authors.lastname: Elsholz
authors.forename: Christine
authors.initials: C
authors.lastname: Muth
authors.forename: Peter R
authors.initials: PR
authors.lastname: Girguis
authors.forename: Roberto
authors.initials: R
authors.lastname: Kolter
authors.forename: Richard
authors.initials: R
authors.lastname: Losick
mesh_terms: D001412:Bacillus subtilis / Q000187:drug effects / Q000201:enzymology / Q000235:genetics / Q000502:physiology*; D001426:Bacterial Proteins / Q000378:metabolism*; D018441:Biofilms; D003580:Cytochromes / Q000378:metabolism*; D005109:Extracellular Matrix / Q000187:drug effects / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D000071677:Histidine Kinase; D007501:Iron / Q000494:pharmacology; D009154:Mutation; D009243:NAD / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism; D011485:Protein Binding; D011494:Protein Kinases / Q000378:metabolism*; D014131:Trace Elements / Q000494:pharmacology
chemical_list: D001426:Bacterial Proteins; D003580:Cytochromes; D014131:Trace Elements; D009243:NAD; D007501:Iron; D011494:Protein Kinases; D000071677:Histidine Kinase; D010100:Oxygen