Protein Export and Surface Anchoring in Gram+ Bacteria

革兰氏细菌中的蛋白质输出和表面锚定

• 批准号: 7009999
• 负责人: June R Scott
• 金额: $ 29.88万
• 依托单位: EMORY UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-09-30 至 2008-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7009999
• 关键词: Streptococcus pyogenes; bacteria infection mechanism; cell fusion; cell membrane; cell wall; enzyme activity; enzyme substrate; gene expression; glutamyltransferase; gram positive bacteria; informatics; laboratory mouse; membrane proteins; nucleic acid hybridization; polymerase chain reaction; protein binding; protein transport; proteomics; secretory protein; southern blotting

DESCRIPTION (provided by applicant): Among the low G+C Gram+ bacteria are many important human pathogens, including some classified as potential bioterrorism agents (i.e. Bacillus anthracis, category A and Listeria monocytogenes, category B). Many of these organisms have proteins on their surface that lack typical Sec-dependent N-terminal secretion signals and thus use unknown mechanisms for export through the cell membrane (cm). Some of these proteins are apparently involved in pathogenesis since they are effective for passive immunization of mice. Aims 1 and 2 of this work are directed at identification and characterization of new Sec-independent protein secretion systems in these organisms. Once secreted through the cm in Gram+ organisms, proteins are either released into the extracellular milieu or anchored to the cell surface. The general mechanism for anchoring proteins to the cell wall (cw) in Gram+ bacteria requires a transpeptidase, called sortase, that recognizes and cleaves a short amino acid motif preceding a C-terminal hydrophobic region and charged tail. We recently characterized two sortases in the group A streptococcus (GAS) that anchor distinct subsets of proteins with the LPXTG motif. At a similar location in the genome of other GAS strains, we have identified genes encoding additional proteins with homology to sortase. In Aim 3 we will characterize the function in the GAS of these proposed new sortases and test their ability to anchor their predicted substrate proteins, which we find encoded nearby. We will also characterize a predicted protein with homology to signal peptidase I (encoded in the same region) that we propose will be needed for secretion of these proteins. The greater understanding of secretion and cell wall anchoring in Gram+ bacteria that results from this work should provide new targets for broad spectrum antibacterial therapy and potential new vaccine vectors. In addition, it should provide commercially useful new methods for large-scale production of proteins.

描述（由申请人提供）：在低的G+ C gram+细菌中，有许多重要的人类病原体，包括一些被归类为潜在的生物恐怖剂（即炭疽芽孢杆菌，A类和单核细胞增生李斯特菌，B类B）。这些生物中的许多生物具有蛋白质的表面蛋白质，缺乏典型的SEC依赖性N末端分泌信号，因此使用未知的机制通过细胞膜（CM）出口。这些蛋白质中的一些显然参与了发病机理，因为它们对小鼠的被动免疫有效。这项工作的目的1和2是针对这些生物体中新的独立于SEC独立蛋白质分泌系统的鉴定和表征。一旦通过革兰氏+生物中的CM分泌，蛋白质要么释放到细胞外环境中，要么锚定在细胞表面上。将蛋白质锚定在革兰氏+细菌中的细胞壁（CW）的一般机制需要一个称为分子酶的转肽酶，该酶识别并裂解在C末端疏水区和带电的尾巴之前的短氨基酸基序。我们最近在A组中表征了两种链球菌（气体），它们用LPXTG基序锚定了不同的蛋白质子集。在其他气体菌株的基因组中的类似位置，我们已经鉴定出编码具有同源性分析酶的其他蛋白质的基因。在AIM 3中，我们将表征这些提出的新排序酶的气体中的功能，并测试它们锚定预测的底物蛋白的能力，我们发现附近编码了它们。我们还将表征具有同源性的预测蛋白质，以信号肽酶I（在同一区域编码），我们建议将这些蛋白质分泌。对革兰氏+细菌中的分泌和细胞壁锚定的更深入的理解应为广谱抗菌治疗和潜在的新疫苗载体提供新的靶标。此外，它应该为大规模生产蛋白质提供商业上有用的新方法。