Suppression of a signaling defect during Myxococcus xanthus development.
The csgA gene encodes an extracellular protein that is essential for cell-cell communication (C-signaling) during fruiting body development of Myxococcus xanthus. Two transposon insertions in the socABC operon, soc-560 and socC559, restore development to csgA null mutants. Mixing soc-560 csgA cells or socC559 csgA cells with csgA cells at a ratio of 1:1 stimulated the development of csgA cells, suggesting that soc mutations allow cells to produce the C-signal or a similar molecule via a csgA-independent mechanism. The socABC operon contains the following three genes: socA, a member of the short-chain alcohol dehydrogenase gene family; socB, a gene encoding a putative membrane anchoring protein; and socC, a negative autoregulator of socABC operon expression. Both suppressor mutations inactivate socC, leading to a 30- to 100-fold increase in socA transcription; socA expression in suppressor strains is at least 100-fold higher than csgA expression during all stages of development. The amino acid sequence of SocA has 28% identity and 51% similarity with that of CsgA. We suggest that CsgA suppression is due to overproduction of SocA, which can substitute for CsgA. These results raise the possibility that a cell surface dehydrogenase plays a role in C-signaling.
Lee
K
K
Department of Microbiology, University of Georgia, Athens 30602, USA.
Shimkets
L J
LJ
D000426:Alcohol Dehydrogenase / Q000235:genetics; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D004268:DNA-Binding Proteins / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D005809:Genes, Regulator; D005816:Genetic Complementation Test; D008969:Molecular Sequence Data; D016296:Mutagenesis; D016941:Myxococcus xanthus / Q000235:genetics / Q000254:growth & development*; D009876:Operon / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D012045:Regulatory Sequences, Nucleic Acid; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction / Q000235:genetics*; D013379:Substrate Specificity; D014158:Transcription, Genetic; D001616:beta-Galactosidase / Q000096:biosynthesis / Q000235:genetics
D001426:Bacterial Proteins; C063576:CsgA protein, Myxococcus xanthus; D004268:DNA-Binding Proteins; D011993:Recombinant Fusion Proteins; C098047:SocC protein, Myxococcus xanthus; D000426:Alcohol Dehydrogenase; D001616:beta-Galactosidase