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首页> 外文期刊>Applied Microbiology >Alternative Sigma Factors SigF, SigE, and SigG Are Essential for Sporulation in Clostridium botulinum ATCC 3502
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Alternative Sigma Factors SigF, SigE, and SigG Are Essential for Sporulation in Clostridium botulinum ATCC 3502

机译：替代西格玛因子SigF，SigE和SigG对肉毒梭菌ATCC 3502中的孢子形成至关重要

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Clostridium botulinum produces heat-resistant endospores that may germinate and outgrow into neurotoxic cultures in foods. Sporulation is regulated by the transcription factor Spo0A and the alternative sigma factors SigF, SigE, SigG, and SigK in most spore formers studied to date. We constructed mutants of sigF , sigE , and sigG in C. botulinum ATCC 3502 and used quantitative reverse transcriptase PCR and electron microscopy to assess their expression of the sporulation pathway on transcriptional and morphological levels. In all three mutants the expression of spo0A was disrupted. The sigF and sigE mutants failed to induce sigG and sigK beyond exponential-phase levels and halted sporulation during asymmetric cell division. In the sigG mutant, peak transcription of sigE was delayed and sigK levels remained lower than that in the parent strain. The sigG mutant forespore was engulfed by the mother cell and possessed a spore coat but no peptidoglycan cortex. The findings suggest that SigF and SigE of C. botulinum ATCC 3502 are essential for early sporulation and late-stage induction of sigK , whereas SigG is essential for spore cortex formation but not for coat formation, as opposed to previous observations in B. subtilis sigG mutants. Our findings add to a growing body of evidence that regulation of sporulation in C. botulinum ATCC 3502, and among the clostridia, differs from the B. subtilis model.
机译：肉毒梭菌产生耐热的内生孢子，该内生孢子可能发芽并长出食物中的神经毒性培养物。迄今为止，在大多数研究过的孢子形成物中，孢子形成受转录因子Spo0A和其他σ因子SigF，SigE，SigG和SigK的调节。我们在肉毒梭菌ATCC 3502中构建了sigF，sigE和sigG的突变体，并使用定量逆转录酶PCR和电​​子显微镜在转录和形态学水平上评估了孢子形成途径的表达。在所有三个突变体中，spo0A的表达均被破坏。 sigF和sigE突变体未能诱导sigG和sigK超过指数期水平，并且在非对称细胞分裂过程中停止了孢子形成。在sigG突变体中，sigE的峰值转录被延迟，并且sigK的水平仍然低于亲本菌株的水平。 sigG突变体的前孢子被母细胞吞没，并具有孢子外壳，但没有肽聚糖皮质。这些发现表明，肉毒梭菌ATCC 3502的SigF和SigE对于sigK的早期孢子形成和后期诱导必不可少，而SigG对于孢子皮层的形成必不可少，但对于外皮的形成则不重要，这与以前在枯草芽孢杆菌sigG中的观察相反。突变体。我们的发现增加了越来越多的证据，表明肉毒梭菌ATCC 3502和梭菌中的孢子形成调节与枯草芽孢杆菌模型不同。

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