Budin-Verneuil Aurélie, Pichereau Vianney, Auffray Yanick, Ehrlich Dusko, Maguin Emmanuelle
Laboratoire Microbiologie de l'Environnement, EA956 - USC INRA 2017, Université de Caen, Caen, France.
Proteomics. 2007 Jun;7(12):2038-46. doi: 10.1002/pmic.200600773.
To cope with medium acidity, Lactococcus lactis has evolved a number of inducible mechanisms commonly referred as acid stress response. To better understand the molecular basis of this response, several mutants constitutively tolerant to acidity were previously obtained by insertional random mutagenesis of L. lactis MG1363. Mutants in which the GMP synthase gene (i.e. guaA), the (p)ppGpp synthase gene (i.e. relA*) or the high affinity phosphate transport system (i.e. pstS) are inactivated are further characterized in this study. 2-DE was performed and showed that 42, 26, and 35 protein spots are positively deregulated in the guaA, relA*, and pstS mutants, respectively, as compared to the wild-type strain. Most of these proteins were identified by MS. Proteomes comparison of the mutants guaA, relA*, and pstS as well as the acid adaptation proteome of the wild-type strain revealed (i) the presence of numerous overlaps and (ii) that only five proteins were overexpressed in the four conditions, suggesting that these proteins play a crucial role in the constitutive acid stress tolerance of the mutants and in the acid tolerance response of the wild-type strain.
为了应对中等酸度，乳酸乳球菌进化出了许多诱导机制，通常称为酸应激反应。为了更好地理解这种反应的分子基础，先前通过对乳酸乳球菌MG1363进行插入随机诱变获得了几种对酸度具有组成型耐受性的突变体。在本研究中，对GMP合酶基因（即guaA）、（p）ppGpp合酶基因（即relA*）或高亲和力磷酸盐转运系统（即pstS）失活的突变体进行了进一步表征。进行了二维电泳，结果表明，与野生型菌株相比，guaA、relA和pstS突变体中分别有42、26和35个蛋白质斑点正向去调节。这些蛋白质中的大多数通过质谱鉴定。guaA、relA和pstS突变体的蛋白质组比较以及野生型菌株的酸适应蛋白质组揭示了（i）存在大量重叠，以及（ii）在这四种条件下只有五种蛋白质过表达，这表明这些蛋白质在突变体的组成型酸应激耐受性和野生型菌株的酸耐受性反应中起关键作用。
