Ebner Patrick, Rinker Janina, Götz Friedrich
Microbial Genetics, Interfaculty Institute of Microbiology and Infection Medicine (IMIT), University of Tübingen, Auf der Morgenstelle 28, 72076, Tübingen, Germany.
Curr Genet. 2016 Feb;62(1):19-23. doi: 10.1007/s00294-015-0504-z. Epub 2015 Jul 7.
The excretion of cytoplasmic proteins (ECP) is a long-known phenomenon in bacteria and eukaryotes. So far, it was not possible to associate either a signal peptide-dependent or a signal peptide-independent pathway to ECP. Nevertheless 25% of the proteins found in Staphylococcus aureus supernatants were cytoplasmic proteins. Because the excreted proteins do not possess a common motive, the most widespread opinion is that ECP is due to cell lysis. This explanation seems to be too easy since several indications imply that there exists a yet unknown mechanism for ECP. Certainly, the up-regulation of autolysins as well as decreased peptidoglycan cross-linking increased ECP. However, in recent years, several evidences arose that cell lysis is not the only reason for ECP. It seems that ECP is a part of the normal cell cycle of S. aureus as it turned out that ECP with several model proteins occurs mainly during cell growth. It has common features as proteins secreted via the Sec translocon and finally the excretion site is the cross wall of dividing cells.
细胞质蛋白的分泌（ECP）在细菌和真核生物中是一个早已为人所知的现象。到目前为止，还无法将依赖信号肽或不依赖信号肽的途径与ECP联系起来。然而，在金黄色葡萄球菌上清液中发现的25%的蛋白质是细胞质蛋白。由于分泌的蛋白质没有共同的基序，最普遍的观点是ECP是由于细胞裂解。这种解释似乎过于简单，因为有几个迹象表明存在一种尚未知晓的ECP机制。当然，自溶素的上调以及肽聚糖交联的减少会增加ECP。然而，近年来，出现了一些证据表明细胞裂解不是ECP的唯一原因。似乎ECP是金黄色葡萄球菌正常细胞周期的一部分，因为事实证明，带有几种模型蛋白的ECP主要发生在细胞生长期间。它具有与通过Sec转位酶分泌的蛋白质相同的特征，最终的分泌位点是正在分裂的细胞的横壁。
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