Molecular Mechanisms of Organelle Assembly by the Prokaryotic Actin Homolog MamK

原核肌动蛋白同源物 MamK 组装细胞器的分子机制

• 批准号: 8059670
• 负责人: Arash Komeili
• 金额: $ 28.58万
• 依托单位: UNIVERSITY OF CALIFORNIA BERKELEY
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-04-01 至 2014-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8059670
• 关键词: Actins; Bacteria; Biochemical; Biogenesis; Biological; Cell Shape; Cell division; Cell physiology; Cells; Cellular biology; Chromosome Segregation; Collaborations; Complex; Cytoskeletal Filaments; Cytoskeletal Proteins; Drug Delivery Systems; Environment; Eukaryota; Eukaryotic Cell; Evolution; Filament; Genes; Genetic; Genomics; Goals; Growth; Health; Homologous Gene; Homology Modeling; In Vitro; Intermediate Filaments; Island; Kinetics; Light; Lipid Bilayers; Magnetism; Magnetospirillum; Maintenance; Mediating; Membrane; Microfilaments; Molecular; Mutagenesis; Mutate; Organelles; Organism; Oxidation-Reduction; Oxygen; Pharmaceutical Preparations; Phylogenetic Analysis; Plasmids; Play; Process; Prokaryotic Cells; Property; Proteins; Recruitment Activity; Research; Role; Series; Set protein; Solvents; Sorting - Cell Movement; Structure; Surface; System; Trees; Tubulin; Ursidae Family; Work; antimicrobial drug; base; combat; design; genetic analysis; in vivo; insight; interest; magnetosomes; membrane biogenesis; mutant; nanoscale; pathogenic bacteria; polymerization; research study; segregation

DESCRIPTION (provided by applicant): Advances in understanding the molecular mechanisms underlying the ultrastructural organization of bacterial cells have blurred the traditional boundaries used to distinguish eukaryotic cells from their prokaryotic counterparts. Most significant amongst these has been the demonstration that prokaryotic organisms contain functional and structural homologs of eukaryotic tubulin, actin and intermediate filaments. These cytoskeletal proteins are essential for cell division, cell shape maintenance and chromosome segregation in a variety of prokaryotic species and hold promise as targets for the discovery of new antimicrobial agents. Recently, we showed the bacterial actin homolog, MamK, is required for the subcellular organization of the magnetosome organelles of magnetotactic bacteria. These membranous organelles, used by the organism to produce nanometer-sized magnetic crystals, are organized as chains within the cell and surrounded by a distinct cytoskeletal network of filaments. In the absence of MamK this network of filaments fails to form and the magnetosomes are dispersed throughout the cell. Phylogenetic analysis shows that MamK is found outside of the magnetotactic bacteria and that it forms a distinct branch of the bacterial actin like proteins. Since it is not essential for survival and has a distinct localization within the cell it may serve as a tractable system for in-depth analysis of bacterial actin-like proteins in general. We have the following goals for this proposal. 1) Define the biochemical and biophysical properties of MamK in vitro. 2) Identify functional domains on the surface of MamK through a global mutagenesis strategy followed by a series of in vivo analyses. 3) Identify and define the function of MamK-interacting proteins. 4) Determine the genes involved in MamK assembly and magnetosome membrane formation through a genetic analysis of the magnetosome island, a large genomic region containing most of the known magnetosome genes. In addition to their relevance to bacterial actin homologs in general these findings will provide insights into the process of organelle formation in bacteria. PUBLIC HEALTH RELEVANCE: Prokaryotes have been shown to contain functional and structural homologs of eukaryotic actin, tubulin and intermediate filaments. These proteins play central roles in organizing cell shape and cell division and are promising drug targets in combating pathogenic bacteria. Understanding the mechanisms that control the action of a bacterial actin homolog will provide important information for the rational design of such drugs and will elucidate key aspects of cellular organization in prokaryotes.

描述（由申请人提供）：在理解细菌细胞超微结构组织的分子机制方面的进展模糊了用于区分真核细胞与其原核对应物的传统界限。其中最重要的是证明原核生物含有真核微管蛋白、肌动蛋白和中间丝的功能和结构同源物。这些细胞骨架蛋白对于多种原核生物的细胞分裂、细胞形状维持和染色体分离是必不可少的，并且有望作为发现新的抗菌剂的靶点。最近，我们发现细菌肌动蛋白同源物MamK是趋磁细菌磁小体细胞器亚细胞组织所必需的。这些膜状细胞器被生物体用来产生纳米尺寸的磁性晶体，在细胞内被组织成链，并被独特的细胞骨架细丝网络包围。在没有MamK的情况下，这种细丝网络无法形成，磁小体分散在整个细胞中。系统发育分析表明，MamK被发现以外的趋磁细菌，它形成了一个独特的分支的细菌肌动蛋白样蛋白。由于它不是生存所必需的，并且在细胞内具有独特的定位，因此它可以作为一个易于处理的系统，用于深入分析细菌肌动蛋白样蛋白。我们对这一提议有以下目标。1)定义体外MamK的生物化学和生物物理特性。2)通过全局诱变策略，然后进行一系列体内分析，鉴定MamK表面的功能结构域。3)识别和定义MamK相互作用蛋白的功能。4)通过对磁小体岛（一个包含大多数已知磁小体基因的大型基因组区域）的遗传分析，确定参与MamK组装和磁小体膜形成的基因。除了它们与细菌肌动蛋白同源物的相关性外，这些发现还将为细菌细胞器形成过程提供见解。公共卫生关系：原核生物已被证明含有真核肌动蛋白、微管蛋白和中间丝的功能和结构同源物。这些蛋白质在组织细胞形状和细胞分裂中起着核心作用，并且是对抗病原菌的有希望的药物靶标。了解控制细菌肌动蛋白同系物的作用的机制将为合理设计此类药物提供重要信息，并将阐明原核生物细胞组织的关键方面。