Wilkens M, Villanueva J E, Cofré J, Chnaiderman J, Lagos R
Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago.
J Bacteriol. 1997 Aug;179(15):4789-94. doi: 10.1128/jb.179.15.4789-4794.1997.
Microcin E492 is a polypeptide antibiotic that is produced and excreted by Klebsiella pneumoniae RYC492. The genetic determinants for microcin synthesis and immunity were cloned in Escherichia coli VCS257 into the cosmid vector pHC79, starting from total DNA of K. pneumoniae RYC492. The microcin E492 expressed in E. coli had the same properties as that of K. pneumoniae, i.e., the same molecular weight, the ability to form ionic channels in planar phospholipid bilayers, and essentially identical biological properties. Microcin E492 expression in E. coli, like that in K. pneumoniae, was mainly in the exponential phase of growth, declining in the stationary phase. The immunity determinant was subcloned into the same vector, and its expression was found to disappear in the stationary phase. This phenomenon is not dependent on rpoS, the stationary-phase sigma factor.
微菌素E492是一种由肺炎克雷伯菌RYC492产生并分泌的多肽抗生素。微菌素合成和免疫的遗传决定因素从肺炎克雷伯菌RYC492的总DNA开始，被克隆到大肠杆菌VCS257中的黏粒载体pHC79中。在大肠杆菌中表达的微菌素E492具有与肺炎克雷伯菌相同的特性，即相同的分子量、在平面磷脂双层中形成离子通道的能力以及基本相同的生物学特性。微菌素E492在大肠杆菌中的表达，与在肺炎克雷伯菌中一样，主要处于生长指数期，在稳定期下降。免疫决定因素被亚克隆到同一载体中，发现其表达在稳定期消失。这种现象不依赖于稳定期σ因子rpoS。
