σ M , an ECF RNA polymerase sigma factor of Bacillus subtilis 168, is essential for growth and survival in high concentrations of salt
1999; Wiley; Volume: 32; Issue: 1 Linguagem: Inglês
10.1046/j.1365-2958.1999.01323.x
ISSN1365-2958
AutoresMalcolm J. Horsburgh, Anne Moir,
Tópico(s)Enzyme Structure and Function
ResumoThe Bacillus subtilis 168 genome encodes seven extracytoplasmic function (ECF) RNA polymerase sigma factors of unknown physiological function. The sigM ( yhdM ) gene, encoding an ECF sigma factor σ M , is essential for growth and survival in nutrient broth (NB) containing 1.4 M NaCl. Strains insertionally inactivated in the sigM gene form aberrantly shaped cells, which swell and lyse spontaneously during growth in NB medium containing increased levels (0.35–0.7 M) of a wide range of different salts. The sigM gene was co‐transcribed with the yhdL and yhdK genes with transcription initiating from two promoters, P A and P M . The transcript from P M was not detected in a sigM mutant, indicating that the expression of sigM was positively autoregulated. Expression of sigM was maximal during exponential growth and was increased by 50% in NB medium containing 0.7 M NaCl. The activity of σ M is negatively regulated by the proteins encoded by the yhdL and yhdK genes.
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