Characterization of the dapA - nlpB Genetic Locus Involved in Regulation of Swarming Motility, Cell Envelope Architecture, Hemolysin Production, and Cell Attachment Ability in Serratia marcescens
| Autor: | Shen-Wu Ho, Yu-Tze Horng, Po-Chi Soo, Jun-Rong Wei, Hsin-Chih Lai, Shang-Chen Hsieh |
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| Rok vydání: | 2005 |
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| Zdroj: | Infection and Immunity. 73:6075-6084 |
| ISSN: | 1098-5522 0019-9567 |
| DOI: | 10.1128/iai.73.9.6075-6084.2005 |
| Popis: | Swarming migration of Serratia marcescens requires both flagellar motility and cellular differentiation and is a population-density-dependent behavior. While the flhDC and quorum-sensing systems have been characterized as important factors regulating S. marcescens swarming, the underlying molecular mechanisms are currently far from being understood. Serratia swarming is thermoregulated and is characterized by continuous surface migration on rich swarming agar surfaces at 30°C but not at 37°C. To further elucidate the mechanisms, identification of specific and conserved regulators that govern the initiation of swarming is essential. We performed transposon mutagenesis to screen for S. marcescens strain CH-1 mutants that swarmed at 37°C. Analysis of a “precocious-swarming” mutant revealed that the defect in a conserved dapA Sm -nlpB Sm genetic locus which is closely related to the synthesis of bacterial cell wall peptidoglycan is responsible for the aberrant swarming phenotype. Further complementation and gene knockout studies showed that nlpB Sm , which encodes a membrane lipoprotein, NlpB Sm , but not dapA Sm , is specifically involved in swarming regulation. On the other hand, dapA Sm but not nlpB Sm is responsible for the determination of cell envelope architecture, regulation of hemolysin production, and cellular attachment capability. While the nlpB Sm mutant showed similar cytotoxicity to its parent strain, the dapA Sm mutant significantly increased in cytotoxicity. We present evidence that DapA Sm is involved in the determination of cell-envelope-associated phenotypes and that NlpB Sm is involved in the regulation of swarming motility. |
| Databáze: | OpenAIRE |
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