Parallel pathways of repression and antirepression governing the transition to stationary phase in Bacillus subtilis
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Edited by Sankar Adhya, National Institutes of Health, Bethesda, MD, and approved August 27, 2008 (received for review May 29, 2008)
Abstract
The AbrB protein of the spore-forming bacterium Bacillus subtilis is a repressor of numerous genes that are switched on during the transition from the exponential to the stationary phase of growth. The gene for AbrB is under the negative control of the master regulator for entry into sporulation, Spo0A∼P. It has generally been assumed that derepression of genes under the negative control of AbrB is achieved by Spo0A∼P-mediated repression of abrB followed by rapid degradation of the AbrB protein. Here, we report that AbrB levels do decrease during the transition to stationary phase, but that this decrease is not the entire basis by which AbrB-controlled genes are derepressed. Instead, AbrB is inactivated by the product of a uncharacterized gene, abbA (formerly ykzF), whose transcription is switched on by Spo0A∼P. The abbA gene encodes an antirepressor that binds to AbrB and prevents it from binding to DNA. Combining our results with previous findings, we conclude that Spo0A∼P sets in motion two parallel pathways of repression and antirepression to trigger the expression of diverse categories of genes during the transition to stationary phase.
Footnotes
- †To whom correspondence should be addressed. E-mail: losick{at}mcb.harvard.edu
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Author contributions: A.V.B., L.R.-L., E.C.H., and R.L. designed research; A.V.B., A.C., L.R.-L., and E.C.H. performed research; A.V.B., A.C., L.R.-L., and R.L. analyzed data; and A.V.B. and R.L. wrote the paper.
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↵*Present address: Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD 20892.
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The authors declare no conflict of interest.
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This article is a PNAS Direct Submission.
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This article contains supporting information online at www.pnas.org/cgi/content/full/0805203105/DCSupplemental.
- © 2008 by The National Academy of Sciences of the USA
