Krajčíková Daniela, Bugárová Veronika, Barák Imrich
Department of Microbial Genetics, Institute of Molecular Biology, Slovak Academy of Sciences, Dúbravská cesta 21, 845 51 Bratislava, Slovakia.
Microorganisms. 2021 Jan 30;9(2):285. doi: 10.3390/microorganisms9020285.
endospores are exceptionally resistant cells encircled by two protective layers: a petidoglycan layer, termed the cortex, and the spore coat, a proteinaceous layer. The formation of both structures depends upon the proper assembly of a basement coat layer, which is composed of two proteins, SpoIVA and SpoVM. The present work examines the interactions of SpoIVA and SpoVM with coat proteins recruited to the spore surface during the early stages of coat assembly. We showed that the alanine racemase YncD associates with two morphogenetic proteins, SpoIVA and CotE. Mutant spores lacking the gene were less resistant against wet heat and germinated to a greater extent than wild-type spores in the presence of micromolar concentrations of l-alanine. In seeking a link between the coat and cortex formation, we investigated the interactions between SpoVM and SpoIVA and the proteins essential for cortex synthesis and found that SpoVM interacts with a penicillin-binding protein, SpoVD, and we also demonstrated that SpoVM is crucial for the proper localization of SpoVD. This study shows that direct contacts between coat morphogenetic proteins with a complex of cortex-synthesizing proteins could be one of the tools by which bacteria couple cortex and coat formation.
芽孢是具有极强抗性的细胞，被两层保护层环绕：一层是肽聚糖层，称为皮层；另一层是芽孢衣，为蛋白质层。这两种结构的形成都依赖于由两种蛋白质SpoIVA和SpoVM组成的基底涂层的正确组装。本研究考察了SpoIVA和SpoVM与在芽孢衣组装早期阶段招募到芽孢表面的芽孢衣蛋白之间的相互作用。我们发现丙氨酸消旋酶YncD与两种形态发生蛋白SpoIVA和CotE相关联。缺乏该基因的突变芽孢对湿热的抗性较低，在微摩尔浓度的L-丙氨酸存在下，其发芽程度比野生型芽孢更高。在探寻芽孢衣与皮层形成之间的联系时，我们研究了SpoVM与SpoIVA以及皮层合成所必需的蛋白质之间的相互作用，发现SpoVM与一种青霉素结合蛋白SpoVD相互作用，并且我们还证明SpoVM对于SpoVD的正确定位至关重要。这项研究表明，芽孢衣形态发生蛋白与皮层合成蛋白复合物之间的直接接触可能是细菌将皮层和芽孢衣形成相耦合的工具之一。
