Mapping of the interactions between partition proteins Delta and Omega of plasmid pSM19035 from Streptococcus pyogenes
Mapping of the interactions between partition proteins Delta and Omega of plasmid pSM19035 from Streptococcus pyogenes
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DOI：
10.1099/mic.0.045369-0
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发表时间：
2011-04-01
期刊：
影响因子：
2.8
通讯作者：
Jagura-Burdzy, Grazyna
中科院分区：
文献类型：
--
作者：
Dmowski, Michal;Jagura-Burdzy, Grazyna
Segrosome 是一种核蛋白复合物，对于质粒分区系统的正常功能至关重要，其形成涉及特定分区蛋白（ParA 样和 ParB 样）、ATP 和特定 DNA 序列（着丝粒位点）之间的相互作用。尽管分区系统已研究多年，但segrosome形成的细节尚不清楚。 pSM19035编码分区系统的组织是独一无二的；与其他已知的 par 系统相比，这里的 delta 和 omega 基因不构成操纵子。此外，Omega [一种具有 Ribbon-Helix-Helix (RHH) 结构的 ParB 样蛋白] 可识别位于 delta、omega 和 copS（拷贝数控制基因）启动子中的多个着丝粒序列。 ParA 样蛋白 Delta 是一种 Walker 型 ATP 酶。在这项工作中，我们确定了 pSM19035 质粒的 Delta 和 Omega 蛋白的二聚化和异质相互作用的相互作用域和要求。 RHH 结构参与体内 Omega 二聚化，其 N 端非结构化部分对于体内和体外与 Delta 的结合都是不可或缺的。 Omega 不需要形成二聚体即可与 Delta 相互作用。 ATP 结合对于 Delta 二聚化不是必需的，但对于体内与 Omega 的相互作用很重要。 Delta 和 Omega 之间的体外相互作用取决于 ATP，但不需要 Omega 识别的特定 DNA 片段（着丝粒）的存在。 Delta 蛋白的 C 末端部分 (aa 198-284) 对于与 Omega 的相互作用是不可或缺的。 Delta 最有可能以二聚体形式与 Omega 相互作用，因为 A' 和 B 基序之间的保守区域中的两个氨基酸取代消除了 Delta 的二聚化及其与 Omega 的相互作用。
Formation of the segrosome, a nucleoprotein complex crucial for proper functioning of plasmid partition systems, involves interactions between specific partition proteins (ParA-like and ParB-like), ATP and specific DNA sequences (the centromeric sites). Although partition systems have been studied for many years, details of the segrosome formation are not yet clear. Organization of the pSM19035-encoded partition system is unique; in contrast with other known par systems, here, the delta and omega genes do not constitute an operon. Moreover, Omega [a ParB-like protein which has a Ribbon-Helix-Helix (RHH) structure] recognizes multiple centromeric sequences located in the promoters of delta, omega and copS (copy-number control gene). The ParA-like protein Delta is a Walker-type ATPase. In this work, we identify the interaction domains and requirements for dimerization and hetero-interactions of the Delta and Omega proteins of pSM19035 plasmid. The RHH structures are involved in Omega dimerization in vivo and its N-terminal unstructured part is indispensable for association with Delta, both in vivo and in vitro. Omega does not need to form dimers to interact with Delta. ATP binding is not required for Delta dimerization but is important for interaction with Omega in vivo. The in vitro interaction between Delta and Omega depends on ATP but does not require the presence of specific DNA segments (the centromere) recognized by Omega. The C-terminal part of the Delta protein (aa 198-284) is indispensable for interaction with Omega. Delta most probably interacts with Omega as a dimer since two amino acid substitutions in a conserved region between the A' and B motifs abolish both the dimerization of Delta and its interaction with Omega.