一种广泛存在的细菌蛋白在转化过程中的关键突触前作用：DprA将进入的单链DNA传递给RecA。

A key presynaptic role in transformation for a widespread bacterial protein: DprA conveys incoming ssDNA to RecA.

作者信息

Mortier-Barrière Isabelle, Velten Marion, Dupaigne Pauline, Mirouze Nicolas, Piétrement Olivier, McGovern Stephen, Fichant Gwennaele, Martin Bernard, Noirot Philippe, Le Cam Eric, Polard Patrice, Claverys Jean-Pierre

机构信息

Laboratoire de Microbiologie et Génétique Moléculaires, UMR 5100 CNRS-Université Paul Sabatier, 118 route de Narbonne, 31062 Toulouse Cedex 09, France.

出版信息

Cell. 2007 Sep 7;130(5):824-36. doi: 10.1016/j.cell.2007.07.038.

DOI:10.1016/j.cell.2007.07.038

PMID:17803906

Abstract

Natural transformation is a mechanism for genetic exchange in many bacterial genera. It proceeds through the uptake of exogenous DNA and subsequent homology-dependent integration into the genome. In Streptococcus pneumoniae, this integration requires the ubiquitous recombinase, RecA, and DprA, a protein of unknown function widely conserved in bacteria. To unravel the role of DprA, we have studied the properties of the purified S. pneumoniae protein and its Bacillus subtilis ortholog (Smf). We report that DprA and Smf bind cooperatively to single-stranded DNA (ssDNA) and that these proteins both self-interact and interact with RecA. We demonstrate that DprA-RecA-ssDNA filaments are produced and that these filaments catalyze the homology-dependent formation of joint molecules. Finally, we show that while the Escherichia coli ssDNA-binding protein SSB limits access of RecA to ssDNA, DprA lowers this barrier. We propose that DprA is a new member of the recombination-mediator protein family, dedicated to natural bacterial transformation.

摘要

自然转化是许多细菌属中进行基因交换的一种机制。它通过摄取外源DNA并随后依赖同源性整合到基因组中进行。在肺炎链球菌中，这种整合需要普遍存在的重组酶RecA和DprA，DprA是一种功能未知但在细菌中广泛保守的蛋白质。为了阐明DprA的作用，我们研究了纯化的肺炎链球菌蛋白及其枯草芽孢杆菌直系同源物（Smf）的特性。我们报告称，DprA和Smf协同结合单链DNA（ssDNA），并且这些蛋白质既能自身相互作用，也能与RecA相互作用。我们证明了能产生DprA-RecA-ssDNA细丝，并且这些细丝催化了依赖同源性的连接分子的形成。最后，我们表明，虽然大肠杆菌单链DNA结合蛋白SSB限制了RecA与ssDNA的结合，但DprA降低了这一障碍。我们提出，DprA是重组介导蛋白家族的一个新成员，专门负责细菌的自然转化。