Altered srf expression in Bacillus subtilis resulting from changes in culture pH is dependent on the Spo0K oligopeptide permease and the ComQX system of extracellular control
Altered srf expression in Bacillus subtilis resulting from changes in culture pH is dependent on the Spo0K oligopeptide permease and the ComQX system of extracellular control
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DOI：
10.1128/jb.180.6.1438-1445.1998
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发表时间：
1998-03-01
影响因子：
3.2
通讯作者：
Zuber, P
中科院分区：
文献类型：
--
作者：
Cosby, WM;Vollenbroich, D;Zuber, P
枯草芽孢杆菌srf操纵子编码表面素合成酶和能力调节蛋白ComS，当细胞生长在富含葡萄糖和谷氨酰胺的培养基中，后期培养pH为5.0或更低时，其表达量降低。表面素合成酶亚基和表面素本身的产生也减少了。将pH升高到接近中性导致srf表达和表面素产生的急剧增加，这种明显依赖于pa的srf表达诱导需要spo0K，它编码寡肽渗透酶，该酶在细胞密度依赖的孢子形成和能力控制中起作用。在低ph和高ph条件下，srf的最佳表达都需要ComP和ComA这对刺激细胞密度依赖性srf转录的双组分调控对，但ph依赖性srf诱导不需要ComP。已知的srf负调控因子RapC和CodY在pa依赖性srf表达中没有显著作用。在低密度培养细胞中，低pH的生长后期培养上清对诱导srf表达没有活性，但当其pH升高到接近中性时，这里呈现出活性，在中性pH下，srf- lacz的细胞外诱导需要ComQ（很可能是诱导srf的信息素ComS和Spo0K）。结果表明，srf的表达响应于培养pH的变化，需要Spo0K和另一种尚未确定的细胞外因子。该研究还提供了与ComP在昏迷调节中有正负两种作用的假设相一致的证据，这两种活动都是由ComS信息素控制的。
The expression of the srf operon of Bacillus subtilis, encoding surfactin synthetase and the competence regulatory protein ComS, was observed to be reduced when cells were grown in a rich glucose-and glutamine-containing medium in which late-growth culture pH was 5.0 or lower. The production of the surfactin synthetase subunits and of surfactin itself was also reduced. Raising the pH to near neutrality resulted in dramatic increases in srf expression and surfactin production, This apparent pa-dependent induction of srf expression required spo0K, which encodes the oligopeptide permease that functions in cell-density dependent control of sporulation and competence? but not CSF, the competence-inducing pheromone that regulates srf expression in a Spo0K-dependent manner, Both ComP and ComA, the two-component regulatory pair that stimulates cell-density-dependent srf transcription, were required for optimal expression of srf at low and high pHs, but ComP was not required for pH-dependent srf induction, The known negative regulators of srf, RapC and CodY, were found not to function significantly in pa-dependent srf expression, Late-growth culture supernatants at low pH were not active in inducing srf expression in cells of low-density cultures but Here rendered active when their pH was raised to near neutrality, ComQ (and very likely the srf-inducing pheromone ComS and Spo0K were found to be required for the extracellular induction of srf-lacZ at neutral PH The results suggest that srf expression, in response to changes in culture pH, requires Spo0K and another, as Set unidentified, extracellular, factor, The study also provides evidence consistent with the hypothesis that ComP acts both positively and negatively in the regulation of ComA and that both activities are controlled by the ComS pheromone.