title: A sigma(54) activator protein necessary for spore differentiation within the fruiting body of Myxococcus xanthus.
abstract: Insertion of an internal DNA fragment into the act1 gene, which encodes one of several sigma(54)-activator proteins in Myxococcus xanthus, produced a mutant defective in fruiting body development. While fruiting-body aggregation appears normal in the mutant, it fails to sporulate (<10(-6) the wild-type number of viable spores). The A and C intercellular signals, which are required for sporulation, are produced by the mutant. But, while it produces A-factor at levels as high as that of the wild type, the mutant produces much less C-signal than normal, as measured either by C-factor bioassay or by the total amount of C-factor protein detected with specific antibody. Expression of three C-factor-dependent reporters is altered in the mutant: the level of expression of Omega4414 is about 15% of normal, and Omega4459 and Omega4403 have alterations in their time course. Finally, the methylation of FrzCD protein is below normal in the mutant. It is proposed that Act1 protein responds to C-signal reception by increasing the expression of the csgA gene. This C-signal-dependent increase constitutes a positive feedback in the wild type. The act1 mutant, unable to raise the level of csgA expression, carries out only those developmental steps for which a low level of C-signaling is adequate.
authors.affiliation: Department of Biochemistry, Stanford University School of Medicine, Stanford, California, USA.
authors.forename: L
authors.initials: L
authors.lastname: Gorski
authors.forename: T
authors.initials: T
authors.lastname: Gronewold
authors.forename: D
authors.initials: D
authors.lastname: Kaiser
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D019677:Artificial Gene Fusion; D001426:Bacterial Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D002352:Carrier Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D012321:DNA-Directed RNA Polymerases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004789:Enzyme Activation; D005798:Genes, Bacterial; D008745:Methylation; D008969:Molecular Sequence Data; D016941:Myxococcus xanthus / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*; D011401:Promoter Regions, Genetic; D051877:RNA Polymerase Sigma 54; D017386:Sequence Homology, Amino Acid; D012808:Sigma Factor / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013171:Spores, Bacterial / Q000502:physiology; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors; D047988:Tumor Necrosis Factor Receptor-Associated Peptides and Proteins
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D001426:Bacterial Proteins; D002352:Carrier Proteins; C063576:CsgA protein, Myxococcus xanthus; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; C065626:FrzCD protein, Myxococcus xanthus; D012808:Sigma Factor; C414202:TRAF3IP2 protein, human; D015534:Trans-Activators; D014157:Transcription Factors; D047988:Tumor Necrosis Factor Receptor-Associated Peptides and Proteins; C092468:spoIIR protein, Bacillus subtilis; C030069:spore-specific proteins, Bacillus; D012321:DNA-Directed RNA Polymerases; D051877:RNA Polymerase Sigma 54