Sensing starvation: a homoserine lactone--dependent signaling pathway in Escherichia coli

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Science  22 Jul 1994:
Vol. 265, Issue 5171, pp. 537-539
DOI: 10.1126/science.7545940


When nutrients become limiting, many bacteria differentiate and become resistant to environmental stresses. For Escherichia coli, this process is mediated by the sigma s subunit of RNA polymerase. Expression of sigma s was induced by homoserine lactone, a metabolite synthesized from intermediates in threonine biosynthesis. Homoserine lactone-dependent synthesis of sigma s was prevented by overexpression of a newly identified protein, RspA. The function of homoserine lactone derivatives in many cell density-dependent phenomena and the similarity of RspA to a Streptomyces ambofaciens protein suggest that synthesis of homoserine lactone may be a general signal of starvation.

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