CHARACTERIZATION OF LEGIONELLA TYPE IV SECRETION SIGNALS

IV 型军团菌分泌信号的特征

基本信息

批准号：
9241342
负责人：
Joseph P Vogel
金额：
$ 22.88万
依托单位：
WASHINGTON UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2016
资助国家：
美国
起止时间：
2016-03-15 至 2020-02-29
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9241342
关键词：
Agrobacterium Alveolar Macrophages Amino Acid Motifs Amino Acid Sequence Amino Acids Antibiotic Resistance Attenuated Bacteria Bacterial Infections Bartonella C-terminal Cells Complement Complex Consensus Consensus Sequence Defect Disease Future Goals Gram-Negative Bacteria Growth Helicobacter Hydrophobicity Immune Infection Injectable Injection of therapeutic agent Investigation Legionella Legionella pneumophila Legionnaires&apos Disease Leucine Mediating Molecular Morbidity - disease rate N-terminal Parasites Pathogenesis Peptide Signal Sequences Plasmids Pneumonia Positioning Attribute Protein Export Pathway Proteins RNA Reporter Reporting Research Resources Scientist Sequence Homology Signal Transduction Stretching System Tertiary Protein Structure Therapeutic Toxin Type III Secretion System Pathway Type IV Secretion System Pathway Virulence Work base design extracellular fungus in vivo mortality mutant novel pathogen public health relevance restoration

项目摘要

DESCRIPTION (provided by applicant): A significant amount of global morbidity and mortality is caused by bacterial pathogens, most of which cause disease by destroying host immune cells or employing them as protected intracellular niches for replication. In order to accomplish this, pathogens must secrete toxins into the extracellular milieu or inject effector molecules into host cells. As a result, the investigation of secretion systems and their substrates has been a major focus of bacterial pathogenesis research. One key to export of toxins/effectors is recognition of the substrate by the secretion system; the protein domain responsible for this is commonly referred to as a signal sequence. Gram-negative bacteria employ a variety of specialized secretion systems during pathogenesis and these have been classified as type I-IX, based on the homology of their components. Type IV secretion systems (T4SSs) consist of plasmid transfer systems, often involved in antibiotic resistance, and adapted conjugation systems, which are commonly used by a variety of intracellular pathogens. Legionella pneumophila, a Gram-negative bacterium that causes pneumonia by replicating inside alveolar macrophages, employs a type IV secretion system called Dot/Icm. The L. pneumophila Dot/Icm T4SS is an amazingly robust apparatus as it injects approximately three hundred different effectors, which will be referred to as Legionella Dot/Icm translocated substrates (LDTSs), into the host cell. It has been proposed that the signal sequence for LDTSs consists of the last ~20 amino acids of each protein. However, this has not been experimentally confirmed for the majority of substrates, and the lack of sequence homology between LDTSs in this region called this idea into question. Although several consensus sequences have been proposed, they reflect only a fraction of the total number of LDTSs that have been identified. In addition, it was recently reported that the LDTS SidJ contains both a C-terminal and an internal signal sequence that function redundantly to export the protein, although strikingly only the internal motif is required during infection. This proposal will utilize a novel experimental approach to identify key features of the C- terminal signal sequence (Aim#1), and then discover additional LDTSs that contain an internal signal sequence (Aim#2).

描述（由申请人提供）：大量的全球发病率和死亡率是由细菌病原体引起的，其中大多数是通过破坏宿主免疫细胞或将其用作受保护的细胞内生态位来引起疾病的。为了实现这一点，病原体必须分泌。因此，分泌系统及其底物的研究一直是细菌发病机制研究的重点之一。毒素/效应物是分泌系统对底物的识别；负责此的蛋白质结构域通常被称为信号序列，革兰氏阴性细菌在发病过程中采用各种专门的分泌系统，这些系统被归类为 I 型。 IX，基于其组件的同源性。IV 型分泌系统（T4SS）由质粒转移系统（通常涉及抗生素耐药性）和适应的接合系统（常被多种细胞内病原体使用）组成。嗜肺军团菌是一种革兰氏阴性细菌，通过在肺泡巨噬细胞内复制而引起肺炎，它采用一种称为 Dot/Icm 的 IV 型分泌系统。嗜肺军团菌 Dot/Icm T4SS 是一种非常强大的装置，因为它注入了大约 300 个不同的效应子。被称为军团菌Dot/Icm易位底物(LDTS)，进入宿主细胞的信号序列已被提出。 LDTS 由每种蛋白质的最后约 20 个氨基酸组成，但是，大多数底物的这一点尚未得到实验证实，并且该区域中 LDTS 之间缺乏序列同源性，使这一想法受到质疑。提出，它们只反映了已识别的 LDTS 总数的一小部分。此外，最近有报道称 LDTS SidJ 包含一个 C 端和一个内部信号序列，其功能是冗余地输出蛋白质，尽管引人注目的是只需要内部主题该提案将利用一种新颖的实验方法来识别关键特征。 C 端信号序列 (Aim#1)，然后发现包含内部信号序列 (Aim#2) 的其他 LDTS。