GENETICS OF POLYPHOSPHATE METABOLISM IN H. PYLORI

描述(由申请人提供)： 幽门螺杆菌(HP)是一种挑剔的微需氧病原体，与消化性溃疡疾病和胃癌有关，将在幽门螺杆菌(Hp)中研究多聚磷(Polyp)代谢的控制。Polyp是一种由数百个磷酸残基组成的长链聚合物，通过高能磷酰键连接在一起。使用快速生长的物种(例如，大肠杆菌、铜绿假单胞菌；在生理上与幽门螺杆菌非常不同)的研究表明，息肉是抗逆性、运动性和毒力等特征所必需的；息肉是由多聚磷酸酶(PPK)形成的，并被PPK或胞外多聚磷酸酶(PPX)消耗。幽门螺杆菌是遗传多样性最强的细菌之一。幽门螺杆菌的一些多样性被认为会影响在代谢基因研究中可能看到的重要的数量表型性状。我们的初步结果表明：(I)ppk1基因对某些HP菌株是必需的，但对其他菌株则不是；(Ii)在ppk1对其来说是可有可无的菌株中，ppk1失活可以阻碍或损害小鼠的生长。拟议的研究有两个具体目标。第一：为了更好地了解ppk1和息肉在幽门螺杆菌中的作用，以及不同菌株在这些作用中的差异。在这里，我们将进一步测试ppk1在某些HP菌株中的推断重要性；选择至少部分补偿ppk1失活的基因或突变等位基因；并研究胞外多聚磷酸酶(PPX)和ppk1之间的相互作用。第二：了解体内对ppk1或息肉的需求是否取决于宿主的基因型或生理，以及ppk1是否主要用于建立或维持感染。这些测试将包括使用在炎症反应(例如，IL-10和IL-12基因敲除)方面明显不同的适当的人幽门螺杆菌小鼠品系以及更宽容的宿主沙鼠进行实验性感染。总的来说，拟议的研究将增加对Hp感染机制和相关疾病的了解，也许还会增加对谁来治疗感染以及这种治疗如何最有效的了解。

DESCRIPTION (provided by applicant): The control of polyphosphate (polyP) metabolism will be studied in Helicobacter pylori (Hp), a fastidious microaerobic pathogen implicated in peptic ulcer disease and gastric cancer. PolyP is a long chain polymer of hundreds of phosphate residues linked by high-energy phosphoanydride bonds. Studies using fast growing species (e.g., E. coli, P. aeruginosa; quite unlike Hp in physiology) indicate that polyP is needed for traits such as stress resistance, motility and virulence; and that polyP is made by polyphosphate kinases (PPK), and consumed by PPK or an exopolyphosphatase (PPX). Hp is one of the most genetically diverse of bacterial species. Some of Hp's diversity is postulated to affect important quantitative phenotypic traits that might be seen in studies of metabolic genes. Our initial results indicate that (i) the ppk1gene is essential for some Hp strains, but not others; and (ii) in strains for which ppk1 is dispensable, ppk1 inactivation can block or impair growth in mice. The proposed studies have two specific aims. First: To better understand roles of ppk1 and polyP in Hp, and diversity among Hp strains in these roles. Here we will further test the inferred essentiality of ppk1 in certain Hp strains; select for genes or mutant alleles that at least partially compensate for ppk1 inactivation; and study the interplay between exopolyphosphatase (PPX) and PPK1. Second: To learn if the need for PPK1 or polyP in vivo depends on host genotype or physiology, and if PPK1 is needed primarily to establish, or also to maintain, infection. These tests will involve experimental infections using appropriate human Hp strains of mouse lines that differ markedly in inflammatory responses (e.g., IL-10 and IL-12 knockout), and also gerbils, a more permissive host. Collectively, the proposed studies will increase understanding of Hp infection mechanisms and associated disease, and perhaps of who to treat for infection and how such treatment can be most effective.