Unexpected parallels between SaPI replication initiators and conserved SCC ORFs

SaPI 复制启动子和保守的 SCC ORF 之间的意外相似之处

• 批准号: 8873188
• 负责人: PHOEBE A RICE
• 金额: $ 23.7万
• 依托单位: UNIVERSITY OF CHICAGO
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-02-01 至 2017-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8873188
• 关键词: ATP phosphohydrolase; ATPase Domain; Address; Adenylyl Imidodiphosphate; Antibiotic Resistance; Appearance; Binding; Biochemical; Biochemistry; Biological Models; Biology; Chromosomes; Complex; Crystallization; Crystallography; DNA; DNA biosynthesis; Data; Data Set; Drug Design; Elements; Enzymes; Event; Excision; Family; Future; Gene Structure; Genes; Genome; Genomic Islands; Homologous Gene; Horizontal Gene Transfer; Housekeeping Gene; L-Selenomethionine; Literature; Medical; Methicillin Resistance; Mobile Genetic Elements; Molecular Biology; Morphology; Open Reading Frames; Pathogenesis; Pathogenicity Island; Pattern; Phase; Proteins; Public Health; Replication Initiation; Replication Origin; Resistance; Site; Staphylococcus aureus; Structure; Superantigens; Testing; Toxin; Variant; Work; base; biochemical tools; clinical practice; ds-DNA; helicase; in vitro activity; in vivo; melting; methicillin resistant Staphylococcus aureus; prevent; public health relevance; recombinase; replication initiator protein; resistance gene

 DESCRIPTION (provided by applicant): This project will investigate a new hypothesis regarding how the mobile genetic element (SCCmec) that carries methicillin resistance spreads among S. aureus strains: We propose that it encodes previously unsuspected functionality for its own replication, which would enhance the efficiency of any horizontal gene transfer mechanism. MRSA (methicillin resistant S. aureus) is a serious and growing public health problem. The recombinases that integrate and excise the SCCmec element into and out of the host genome have been identified and are under study in our lab. However, nothing is known about the events between excision from one genome and appearance in another. While analyzing the conserved ORFs that flank recombinase genes, we realized that some of are likely to have functions in DNA replication. This proposal focuses on a large putative ATPase (Cch) that we discovered is related to the known replication initiation proteins encoded by S. aureus pathogenicity islands (SaPIs). Our preliminary structural and biochemical data suggest that the SCCmec protein in question (Cch) is a self-loading helicase whose closest homologs in the ATPase domain are, surprisingly, the eukaryotic and archaeal replicative MCM helicases. Thus we have determined the first structure of that type of helicase in the active ring form. This work will change how people think about SCCmec elements and how they spread methicillin resistance and will provide new model systems for understanding mechanisms of self-loading and MCM-like helicases. Aim 1: Structural understanding of Cch Aim 2: How structurally similar / different are the subtypes of SaPI / SCC replication initiator? Aim 3: What are the biochemical activities of Cch and SaPI3 rep?

 描述（由申请人提供）：该项目将研究关于携带甲氧西林抗性的移动遗传元件（SCCmec）如何在金黄色葡萄球菌菌株中传播的新假设：我们建议它编码以前未曾怀疑过的自身复制功能，这将增强任何水平基因转移机制的效率。MRSA（耐甲氧西林金黄色葡萄球菌）是一个严重且日益严重的公共卫生问题。进出宿主基因组的 SCCmec 元件已被识别，并正在我们的实验室进行研究。然而，在分析重组酶基因侧翼的保守 ORF 时，我们对从一个基因组切除到在另一个基因组中出现之间的事件一无所知。其中一些可能在 DNA 复制中发挥作用。该提案重点关注我们初步发现的大型假定 ATP 酶 (Cch)，该酶与金黄色葡萄球菌致病性岛 (SaPI) 编码的已知复制起始蛋白有关。结构和生化数据表明，所讨论的 SCCmec 蛋白 (Cch) 是一种自加载解旋酶，令人惊讶的是，其 ATP 酶结构域中最接近的同源物是真核和古细菌复制性 MCM 解旋酶，因此我们确定了该类型的第一个结构。这项工作将改变人们对 SCCmec 元件及其传播甲氧西林耐药性的方式的看法，并将为理解自加载和解旋酶的机制提供新的模型系统。 MCM 样解旋酶 目标 1：Cch 的结构了解 目标 2：SaPI / SCC 复制起始子的亚型在结构上有何相似/不同？ 目标 3：Cch 和 SaPI3 代表的生化活性是什么？