Elucidation of a bacterial cell shape generating program and pathogenic functions

阐明细菌细胞形状生成程序和致病功能

• 批准号: 8256474
• 负责人: Nina Salama
• 金额: $ 42.36万
• 依托单位: FRED HUTCHINSON CANCER RESEARCH CENTER
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-12-01 至 2016-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8256474
• 关键词: Bacteria; Behavior; Binding; Biochemical; Campylobacter jejuni; Cell Shape; Cell Wall; Cells; Clinical; Communicable Diseases; Complex; Cytoskeletal Proteins; Deposition; Disease; Epithelium; Fluorescence-Activated Cell Sorting; Gastric Mucin; Gastritis; Generations; Genes; Genetic Epistasis; Genetic Screening; Goals; Grant; Helicobacter pylori; Homologous Gene; Human; In Vitro; Infection; Learning; Libraries; Life; Membrane Proteins; Mission; Modeling; Modification; Molecular; Molecular Probes; Morphology; Mucous body substance; Names; National Institute of Allergy and Infectious Disease; Outcome; Pathogenesis; Pathway interactions; Penetration; Peptic Ulcer; Peptides; Peptidoglycan; Periplasmic Proteins; Phenotype; Polymers; Population; Proteins; Proteobacteria; Publishing; Resistance; Role; Shapes; Stomach; Swimming; Testing; Thick; Vibrio cholerae; Virulence; Visual; Work; antimicrobial; cell motility; crosslink; design; dimer; gene discovery; malignant stomach neoplasm; monomer; mutant; pathogen; programs; retinal rods; theories

DESCRIPTION (provided by applicant): Helicobacter pylori is a helical rod shaped bacterium that colonizes the human stomach causing clinical outcomes that range from mild gastritis to peptic ulcer and gastric cancers. Most descriptions of H. pylori virulence include the widely-accepted hypothesis that its helical cell shape enhances colonization of the stomach. We recently provided the first experimental support for this theory with the characterization of four cell shape determining genes (csd1, csd2, csd3, ccmA) that promote helical cell curvature and twist through changes in cell wall peptidoglycan (PG) crosslinking and are required for efficient stomach colonization. Alteration of peptide crosslinking within the PG sacculus defines a new mechanism for bacterial cell shape generation; previous studies delineated localized deposition and restriction of new PG deposition as drivers of straight rod and curved rod shapes. Though the mutants described above have lost helical twist, they retain some curvature. Thus much remains to be learned about the precise molecular mechanisms for generating helical shape in H. pylori. This grant builds on our published work with a goal of elucidating the H. pylori helical shape generating program and the contributions of this cell shape program to H. pylori pathogenesis. Aim 1 will identify and characterize additional genes involved in helical cell shape determination. Aim 2 will investigate how these genes work together to promote shape using biochemical studies of cell shape proteins and PG cell wall composition. Aim 3 will investigate possible mechanisms by which the helical cell shape generating program promotes stomach colonization including modulation of swimming behavior and niche utilization within the stomach. Bacteria manifest an impressive diversity of cell shapes that are highly conserved within species but the selective forces leading to conservation of specific shapes are poorly understood. We have established H. pylori as an excellent model to elucidate molecular determinants of helical cell shape and the selective role of shape during host colonization in the Proteobacteria; Csd proteins and CcmA homologues are well conserved among curved to helical Proteobacteria including several other pathogens such as Campylobacter jejuni and Vibrio cholerae. The elucidation of a helical shape generating program required for stomach colonization promises to illuminate new targets for antimicrobial design which are badly needed in H. pylori as current strains display increasing resistance to existing therapies and fits the mission of NIAID to understand and treat infectious diseases. PUBLIC HEALTH RELEVANCE: Evident in its name, Helicobacter pylori is a helical rod shaped bacterium that colonizes the human stomach causing clinical outcomes that range from mild gastritis to peptic ulcer and gastric cancer. We discovered genes that promote helical cell shape by altering the extent of peptide crosslinking in the cell wall. Study of how these cell wall modifications promote helical cell shape and the ability of the bacterium to live in its niche will help us better understand how this bacteria causes disease and uncover new ways to inhibit infection.

描述（由申请人提供）：幽门螺杆菌是一种螺旋杆状细菌，定植于人类胃中，引起从轻度胃炎到消化性溃疡和胃癌的临床结果。大多数对幽门螺杆菌毒力的描述都包括广泛接受的假设，即其螺旋细胞形状增强了胃的定植。我们最近为这一理论提供了第一个实验支持，对四种细胞形状决定基因（csd1、csd2、csd3、ccmA）进行了表征，这些基因通过细胞壁肽聚糖（PG）交联的变化促进螺旋细胞弯曲和扭曲，并且是高效细胞形状决定基因所必需的。胃定植。 PG球囊内肽交联的改变定义了细菌细胞形状生成的新机制；先前的研究将局部沉积和新 PG 沉积的限制描述为直杆和弯杆形状的驱动因素。尽管上述突变体失去了螺旋扭曲，但它们保留了一些曲率。因此，关于幽门螺杆菌产生螺旋形状的精确分子机制还有很多东西有待了解。这项资助建立在我们已发表的工作的基础上，目的是阐明幽门螺杆菌螺旋形状生成程序以及该细胞形状程序对幽门螺杆菌发病机制的贡献。目标 1 将鉴定和表征参与螺旋细胞形状确定的其他基因。目标 2 将通过细胞形状蛋白和 PG 细胞壁组成的生化研究来研究这些基因如何共同作用来促进形状。目标 3 将研究螺旋细胞形状生成程序促进胃定植的可能机制，包括调节游泳行为和胃内生态位利用。细菌表现出令人印象深刻的细胞形状多样性，这些形状在物种内高度保守，但导致特定形状保守的选择力却知之甚少。我们建立了幽门螺杆菌作为一个很好的模型来阐明螺旋细胞形状的分子决定因素以及形状在变形菌中宿主定植过程中的选择性作用； Csd 蛋白和 CcmA 同源物在弯曲到螺旋变形菌中非常保守，包括其他几种病原体，例如空肠弯曲菌和霍乱弧菌。胃定植所需的螺旋形状生成程序的阐明有望阐明抗菌设计的新目标，这是幽门螺杆菌急需的，因为当前菌株对现有疗法的抵抗力不断增强，并且符合 NIAID 理解和治疗传染病的使命。 公共健康相关性：从名字上就可以看出，幽门螺杆菌是一种螺旋杆状细菌，定植于人类胃中，引起从轻度胃炎到消化性溃疡和胃癌等一系列临床后果。我们发现了通过改变细胞壁中肽交联程度来促进螺旋细胞形状的基因。研究这些细胞壁修饰如何促进螺旋细胞形状以及细菌在其生态位中生存的能力将有助于我们更好地了解这种细菌如何引起疾病并发现抑制感染的新方法。