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Structural insight into novel mechanisms of type III secretion

III 型分泌新机制的结构洞察

基本信息

批准号：
10396532
负责人：
CHARALAMPOS KALODIMOS
金额：
$ 44.88万
依托单位：
ST. JUDE CHILDREN'S RESEARCH HOSPITAL
依托单位国家：
美国
项目类别：
财政年份：
2011
资助国家：
美国
起止时间：
2011-12-01 至 2024-04-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10396532
关键词：
ATP phosphohydrolase Animals Anti-Infective Agents Bacterial Proteins Binding Biochemical Biological Assay Bordetella Cell surface Cells Child Mortality Complex Cryoelectron Microscopy Cytosol Data Disease Dysentery Event Filament Food Food Poisoning Gram-Negative Bacteria Human In Vitro Infantile Diarrhea Kinetics Light Locomotion Membrane Molecular Chaperones Morphology Needles Organelles Pathogenesis Pathogenicity Plague Process Protein Export Pathway Protein Secretion Proteins Proton-Motive Force Pseudomonas Recycling Regulation Reporting Resolution Role Salmonella Shigella Signal Transduction Sorting - Cell Movement Specificity Structure System Thermodynamics Time Type III Secretion System Pathway Typhoid Fever Vaccines Virulence Virulence Factors X-Ray Crystallography cell motility design enteropathogenic Escherichia coli in vivo insight kinetosome nanomachine novel operation pathogenic Escherichia coli pathogenic bacteria protein structure structural biology therapeutic protein

项目摘要

Project Summary Type III secretion systems (T3SSs) are nanomachines that are dedicated to protein export in Gram-negative bacteria. T3SSs share the same morphology and overall structure and can be functionally classiﬁed into two evolutionary-related classes: the ﬂagellar T3SS, which promotes bacterial locomotion and motility enabled by the ﬂagellum, and the pathogenic T3SS, which uses the injectisome to transport virulence proteins into human or animal host cells. Over the past decade signiﬁcant progress has been made in understanding the structure, assembly and the mode of operation of T3SS. The principal structural building proteins of the ﬂagellum and the injectisome, from the basal body embedded in the inner and outer bacterial membrane to the tip of the ﬁlaments protruding from the cell surface, and the cytosolic components have been extensively characterized. Flagellar proteins and virulence factors (effectors, needle proteins and translocators) form tight complexes with T3S-dedicated chaperones in the cytosol and are subsequently targeted speciﬁcally to the export apparatus located at the membrane. Powered by ATP and the proton motive force, the ﬂagellar proteins and bacterial effectors are then translocated through the channel. Fundamental questions about the functional mechanisms underpinning these processes remain unaddressed. We propose to use an integrated approach combining structural, dynamic, thermodynamic, kinetic, biochemical and in vitro and in vivo functional assays to provide insight into the early events of the translocation process that involve the recognition mechanisms by chaperones, targeting mechanisms to the ATPase and the sorting platform, selection mechanisms that control the hierarchical transport of the ﬁlament-forming proteins and the effectors and ultimately the assembly of the cytosolic part of the machinery. We have extensively characterized over the last years T3S protein components from the enteropathogenic Escherichia coli (EPEC), the major cause of infantile diarrhea and child mortality worldwide, as well as from Salmonella sp. commonly associated with food poising. We present here novel ﬁndings supporting very intriguing hypotheses about the mechanisms used by T3SSs to carry out their function. The speciﬁc aims are designed to provide atomic-resolution insight into (i) the mechanisms of speciﬁc interactions between and among key T3S proteins, (ii) the mechanistic basis for targeting of T3S proteins to the export gate, (iii) the “recognition” and “secretion” signal, and (iv) the assembly and operation mechanisms of the export gate and ultimately of the entire T3S machinery.

项目总结