Cao Yuan, Bazemore-Walker Carthene R
Brown University Department of Chemistry, Providence, RI 20912, United States.
Brown University Department of Chemistry, Providence, RI 20912, United States.
J Proteomics. 2014 Jan 31;97:187-94. doi: 10.1016/j.jprot.2013.08.011. Epub 2013 Aug 21.
Biotinylation of intact cells, avidin enrichment of derivatized peptides, and shotgun proteomics were employed to reveal the composition of the surface-exposed proteome of the aquatic bacterium, Caulobacter crescentus. Ninety-one unique proteins were identified with the majority originating from the outer membrane, periplasm, and inner membrane, subcellular regions that comprise the Gram-negative bacterium cell envelope. Many of these proteins were described as 'conserved hypothetical protein' or 'hypothetical protein'; and so, the actual expression of these gene products was confirmed. Others did not have any known function or lacked annotation. However, this investigation of the Caulobacter surfaceome did reveal the unanticipated presence of a number of enzymes involved in protein degradation.
The results presented here can provide a starting point for hypothesis-driven research projects focused on this bacterium in particular and centered on understanding Gram-negative cell architecture and outer membrane biogenesis broadly. The detected protein degradation enzymes anchored on or located within the outer membrane suggest that Caulobacter has nutrient sources larger than small molecules and/or further processes surface proteins once secreted to this location. Additionally, confirmation of outer membrane residency of those proteins predicted to be periplasmic or whose location prediction was not definitive could potentially elucidate the identities of Gram-negative specific anchorless surface proteins. This article is part of a Special Issue entitled: Trends in Microbial Proteomics.
采用完整细胞的生物素化、抗生物素蛋白对衍生肽的富集以及鸟枪法蛋白质组学来揭示水生细菌新月柄杆菌表面暴露蛋白质组的组成。共鉴定出91种独特的蛋白质，其中大多数来自外膜、周质和内膜，这些亚细胞区域构成了革兰氏阴性细菌的细胞壁。这些蛋白质中有许多被描述为“保守假设蛋白”或“假设蛋白”；因此，证实了这些基因产物的实际表达。其他一些蛋白质则没有任何已知功能或缺乏注释。然而，对新月柄杆菌表面蛋白质组的这项研究确实揭示了一些参与蛋白质降解的酶的意外存在。
本文给出的结果可以为以该细菌为特定研究对象、以广泛理解革兰氏阴性菌细胞结构和外膜生物发生为核心的假设驱动研究项目提供一个起点。检测到的锚定在外膜上或位于外膜内的蛋白质降解酶表明，新月柄杆菌具有比小分子更大的营养源，和/或在表面蛋白分泌到该位置后对其进行进一步加工。此外，对那些预计位于周质或其位置预测不明确的蛋白质在外膜中的定位进行确认，可能有助于阐明革兰氏阴性菌特异性无锚定表面蛋白的身份。本文是名为《微生物蛋白质组学趋势》的特刊的一部分。
