期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2003
卷号：100
期号：4
页码：2008-2013
DOI：10.1073/pnas.0330944100
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The {delta}-proteobacterium Myxococcus xanthus coordinates its motility during aggregation and fruiting body formation. While searching for chemotaxis genes in M. xanthus, we identified a third chemotaxis-like gene cluster, the che3 cluster, encoding homologs to two methyl-accepting chemotaxis proteins (MCPs), a CheW, a hybrid CheA, a CheB, a CheR, but no CheY. Mutations in mcp3A, mcp3B, and cheA3 did not show obvious defects in motility or chemotaxis but did affect the timing of entry into development. Mutations in these genes caused early aggregation of starving cells, even at low cell densities. Furthermore, these mutants showed pronounced overexpression of the developmentally regulated Tn5lac fusions {Omega}4403, {Omega}4411, and {Omega}4521 as well as overexpression of mbhA and tps, markers for peripheral rods and aggregating cells, respectively. Divergently transcribed from the che3 promoter region is another gene, crdA (chemosensory regulator of development), predicted to encode a transcriptional activator of {sigma}54-dependent promoters. To test the hypothesis that CrdA functions as the cognate response regulator for the histidine kinase CheA3, CrdA and CheA3 were assayed and found to interact strongly in the yeast two-hybrid system. Mutant analysis showed that crdA cells were delayed in development (12-24 h) and delayed in MbhA production relative to the wild type. An mcp3BcrdA double mutant displayed the crdA phenotype, indicating that crdA is epistatic to mcp3B. We conclude that the Che3 chemotaxis-like system functions to control developmental gene expression by regulating a {sigma}54 transcriptional activator, CrdA.
