Public Health Research Institute Center, New Jersey Medical School, Rutgers University, Newark, NJ, USA.
Mol Microbiol. 2021 Jul;116(1):71-79. doi: 10.1111/mmi.14690. Epub 2021 Feb 8.
We show that the ComEB protein is not required for transformation in Bacillus subtilis, despite its expression from within the comE operon under competence control, nor is it required for the correct polar localization of ComGA. We show further that the synthesis of the putative channel protein ComEC is translationally coupled to the upstream comEB open reading frame, so that the translation of comEB and a suboptimal ribosomal-binding site embedded in its sequence are needed for proper comEC expression. Translational coupling appears to be a common mechanism in three major competence operons for the adjustment of protein amounts independent of transcriptional control, probably ensuring the correct stoichiometries for assembly of the transformation machinery. comEB and comFC, respectively, encode cytidine deaminase and a protein resembling type 1 phosphoribosyl transferases and we speculate that nucleotide scavenging proteins are produced under competence control for efficient reutilization of the products of degradation of the non-transforming strand during DNA uptake.
我们表明，ComEB 蛋白尽管在枯草芽孢杆菌的 comE 操纵子中受感受态控制表达，但对于转化并非必需，也不需要 ComGA 的正确极性定位。我们进一步表明，假定通道蛋白 ComEC 的合成与 comEB 开放阅读框的上游翻译偶联，因此 comEB 的翻译和其序列中嵌入的一个不太理想的核糖体结合位点对于正确的 comEC 表达是必需的。翻译偶联似乎是三个主要感受态操纵子中一种常见的机制，用于在不依赖于转录控制的情况下调整蛋白质的数量，可能确保转化机制组装的正确化学计量比。comEB 和 comFC 分别编码胞嘧啶脱氨酶和一种类似于 1 型磷酸核糖基转移酶的蛋白质，我们推测核苷酸捕获蛋白是在感受态控制下产生的，以在摄取 DNA 期间有效再利用非转化链降解产物。
