Sortase B-anchored surface proteins of S.aureus

金黄色葡萄球菌的分选酶 B ​​锚定表面蛋白

• 批准号: 6640181
• 负责人: Olaf Schneewind
• 金额: $ 38.13万
• 依托单位: UNIVERSITY OF CHICAGO
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-06-01 至 2007-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6640181
• 关键词: A kinase anchoring protein; Staphylococcus aureus; aminoacyltransferase; animal tissue; bacteria infection mechanism; bacterial proteins; biological signal transduction; cell wall; enzyme activity; enzyme mechanism; enzyme structure; enzyme substrate; genetic library; iron; membrane transport proteins; mutant; protein structure function; secretion; transposon /insertion element; virulence

DESCRIPTION (provided by applicant): Human infections caused by Staphylococcus aureus present a serious therapeutic challenge due to the appearance of antibiotic-resistant strains. The mechanism of surface protein anchoring to the S. aureus cell wall is examined as a possible target for anti-infective therapy. Staphylococcal surface proteins are synthesized as precursors with an N-terminal signal peptide and a C-terminal sorting signal, containing a LPXTG motif as well as positively charged residues. The charged residues are thought to retain surface proteins within the secretion pathway, allowing sorting signal cleavage between the threonine (T) and the glycine (G) of the LPXTG motif. The carboxyl-group of threonine is subsequently amide-linked to the amino-group of peptidoglycan crossbridges, anchoring the C-terminal ends of surface proteins to the staphylococcal cell wall. Sortase (SrtA), a membrane anchored transpeptidase of S. aureus, is responsible for anchoring surface proteins with a LPXTG motif to the cell wall envelope. We report here the identification of a second sortase (SrtB) in the Gram-positive pathogen Staphylococcus aureus that is required for anchoring of a hitherto unknown surface protein with a NPQTN motif. Purified SrtB cleaves NPQTN-bearing peptides in vitro, and a srtB mutant is defective in the persistence of animal infections. SrtB is part of an iron-regulated locus called iron-responsive surface determinants (isd), which also contains a ferrichrome transporter and surface proteins with NPQTN and LPXTG motifs. Thus, cell wall anchored surface proteins and the isd locus appear to be involved in a novel mechanism of iron acquisition that is important for bacterial pathogenesis. This proposal aims to characterize the role of sortase B in anchoring surface proteins to the cell wall envelope and to study the contribution of SrtB-mediated cell wall sorting during infection. Genetic and biochemical experiments aim at the identification of genes or gene products that are required for the anchoring of NPQTN-sorting signal containing surface proteins to the cell wall envelope. Other experiments examine the physiological role of the isd locus in iron transport.

描述（由申请人提供）：金黄色葡萄球菌引起的人类感染引起了严重的治疗挑战，这是由于抗生素耐药菌菌株的出现。锚定在金黄色葡萄球菌细胞壁上的表面蛋白机理被视为抗感染治疗的可能靶标。将葡萄球菌表面蛋白合成为N端信号肽和C末端分类信号的前体，其中包含LPXTG基序以及带正电荷的残基。人们认为，带电的残基将表面蛋白保留在分泌途径中，从而可以在苏氨酸（T）和LPXTG基序的甘氨酸（t）和甘氨酸（G）之间进行分类。随后将苏氨酸的羧基与酰胺链连接到肽聚糖跨桥的氨基群，将表面蛋白的C末端固定在葡萄球菌细胞壁上。分子酶（SRTA）是金黄色葡萄球菌的膜锚定肽酶，负责将表面蛋白锚定在细胞壁包膜上。 我们在这里报告了革兰氏阳性病原体中第二排序酶（SRTB）的鉴定 金黄色葡萄球菌是锚定具有NPQTN基序的迄今未知表面蛋白所需的。纯化的SRTB在体外切割NPQTN含有NPQTN的肽，而SRTB突变体在动物感染的持续性中有缺陷。 SRTB是一个称为铁反应性表面决定因素（ISD）的铁原点的一部分，该基因座还包含具有NPQTN和LPXTG基序的铁晶体转运蛋白和表面蛋白。因此，细胞壁锚定表面蛋白和ISD基因座似乎参与了一种新的铁采集机制，这对于细菌发病机理很重要。该建议旨在表征分子B在将表面蛋白锚定在细胞壁包膜上的作用，并研究感染过程中SRTB介导的细胞壁分选的贡献。遗传和生化实验旨在鉴定固定含有表面蛋白的NPQTN分类信号所需的基因或基因产物。其他实验检查了ISD基因座在铁运输中的生理作用。