University of Graz, Institute of Molecular Biosciences, Humboldtstrasse 50/I, 8010 Graz, Austria.
Plasmid. 2012 Mar;67(2):128-38. doi: 10.1016/j.plasmid.2011.12.014. Epub 2012 Jan 10.
Bacterial conjugation disseminates genes among bacteria via a process requiring direct cell contact. The cell envelope spanning secretion apparatus involved belongs to the type IV family of bacterial secretion systems, which transport protein as well as nucleoprotein substrates. This study aims to understand mechanisms leading to the initiation of type IV secretion using conjugative plasmid paradigm R1. We analyze the general requirements for plasmid encoded conjugation proteins and DNA sequence within the origin of transfer (oriT) for protein secretion activity using a Cre recombinase reporter system. We find that similar to conjugative plasmid DNA strand transfer, activation of the R1 system for protein secretion depends on binding interactions between the multimeric, ATP-binding coupling protein and the R1 relaxosome including an intact oriT. Evidence for DNA independent protein secretion was not found.
细菌通过需要直接细胞接触的过程进行细菌间的基因传递。所涉及的跨越细胞膜的分泌装置属于细菌 IV 型分泌系统家族，该系统可转运蛋白和核蛋白底物。本研究旨在利用 R1 型可接合性质粒范例来了解引发 IV 型分泌的机制。我们使用 Cre 重组酶报告系统分析了质粒编码的接合蛋白和转移起始区（oriT）内的 DNA 序列对蛋白分泌活性的一般要求。我们发现，类似于可接合性质粒 DNA 链转移，R1 系统蛋白分泌的激活依赖于多聚体、ATP 结合偶联蛋白与包含完整 oriT 的 R1 松弛复合物之间的结合相互作用。未发现 DNA 非依赖性蛋白分泌的证据。
