Wawrzyniak Paweł, Płucienniczak Grażyna, Bartosik Dariusz
Department of Bioengineering, Institute of Biotechnology and Antibiotics, Warsaw, Poland.
Department of Bacterial Genetics, Institute of Microbiology, Faculty of Biology, University of Warsaw, Warsaw, Poland.
Front Microbiol. 2017 Nov 30;8:2353. doi: 10.3389/fmicb.2017.02353. eCollection 2017.
Horizontal gene transfer (HGT) contributes greatly to the plasticity and evolution of prokaryotic and eukaryotic genomes. The main carriers of foreign DNA in HGT are mobile genetic elements (MGEs) that have extremely diverse genetic structures and properties. Various strategies are used for the maintenance and spread of MGEs, including (i) vegetative replication, (ii) transposition (and other types of recombination), and (iii) conjugal transfer. In many MGEs, all of these processes are dependent on rolling-circle replication (RCR). RCR is one of the most well characterized models of DNA replication. Although many studies have focused on describing its mechanism, the role of replication initiator proteins has only recently been subject to in-depth analysis, which indicates their involvement in multiple biological process associated with RCR. In this review, we present a general overview of RCR and its impact in HGT. We focus on the molecular characteristics of RCR initiator proteins belonging to the HUH and Rep_ protein families. Despite analogous mechanisms of action these are distinct groups of proteins with different catalytic domain structures. This is the first review describing the multifunctional character of various types of RCR initiator proteins, including the latest discoveries in the field. Recent reports provide evidence that (i) proteins initiating vegetative replication (Rep) or mobilization for conjugal transfer (Mob) may also have integrase (Int) activity, (ii) some Mob proteins are capable of initiating vegetative replication (Rep activity), and (iii) some Rep proteins can act like Mob proteins to mobilize plasmid DNA for conjugal transfer. These findings have significant consequences for our understanding of the role of RCR, not only in DNA metabolism but also in the biology of many MGEs.
水平基因转移（HGT）对原核生物和真核生物基因组的可塑性及进化有很大贡献。HGT中外来DNA的主要载体是具有极其多样遗传结构和特性的可移动遗传元件（MGEs）。维持和传播MGEs的策略有多种，包括：（i）营养复制；（ii）转座（及其他类型的重组）；（iii）接合转移。在许多MGEs中，所有这些过程都依赖于滚环复制（RCR）。RCR是最具特征的DNA复制模型之一。尽管许多研究集中于描述其机制，但复制起始蛋白的作用直到最近才受到深入分析，这表明它们参与了与RCR相关的多个生物学过程。在本综述中，我们概述了RCR及其在HGT中的影响。我们重点关注属于HUH和Rep_蛋白家族的RCR起始蛋白的分子特征。尽管作用机制类似，但这些是具有不同催化结构域结构的不同蛋白组。这是第一篇描述各类RCR起始蛋白多功能特性的综述，包括该领域的最新发现。最近的报告提供了以下证据：（i）启动营养复制（Rep）或接合转移动员（Mob）的蛋白可能也具有整合酶（Int）活性；（ii）一些Mob蛋白能够启动营养复制（Rep活性）；（iii）一些Rep蛋白可像Mob蛋白一样动员质粒DNA进行接合转移。这些发现对我们理解RCR的作用具有重要意义，不仅在DNA代谢方面，而且在许多MGEs的生物学方面。
