Contribution of catabolite control protein A to group A streptococcal virulence

描述(申请人提供)：在美国，每年被革兰氏阳性细菌感染导致数万人死亡。最近发现，转录调节因子分解代谢控制蛋白A(CCPA)在包括A组链球菌(GAS)在内的许多革兰氏阳性病原菌的标准实验室培养基中影响毒力基因的表达。CCPA最初是在芽孢杆菌中发现的，它与被称为分解代谢反应元件(Cre)的DNA序列结合在一起，并与其辅助因子丝氨酸残基46位磷酸化的组氨酸磷酸蛋白(HPR-Ser46-P)结合。CCPA、HPR和调节HPR磷酸化状态的激酶/磷酸化酶(HPrK/P)的同源基因存在于所有主要的革兰氏阳性人类病原体中，而且越来越多的数据表明CCPA-(HPR-Ser46-P)-HPrK/P轴与多种细菌的感染性有关。该项目的长期目标是明确CCPA-(HPR-Ser46-P)-HPrK/P轴是如何影响GAS毒力的，并确定CCPA在感染过程中影响基因表达的机制。这项建议的具体目的是检验由初步数据产生的假设，这些假说表明：1)CCPA的失活在感染小鼠肌肉期间改变了GAS基因的表达；2)CCPA的失活降低了小鼠肌炎模型中GAS的毒力；3)GAS cre位点的中央CpG突变降低了CCPA-(HPR-Ser46-P)DNA结合亲和力；以及4)CCPA在低水平或不存在HPR-Ser46-P的条件下影响了基因的表达。在目标1中，将在多个感染小鼠模型上进行野生型和CCPA灭活的GAS菌株的基因表达分析，以验证CCPA是GAS感染过程中关键毒力因子调节因子的假设。目的2比较来源于不同M蛋白血清型亲本菌株的CCPA等基因突变株与其亲本野生型菌株在不同小鼠感染模型中的毒力，以验证CCPA对多种M蛋白血清型GAS菌株的感染性有积极作用的假说。在目标3中，将使用体外和体内方法相结合的方法来验证中央cre位点CpG在CCPA对GAS基因表达的影响中起关键作用的假设。目的4比较CCPA和HPR-Ser46-P灭活菌株在不同代谢条件下的基因表达谱，以验证CCPA在缺乏HPR-Ser46-P的情况下影响GAS基因表达的假说。CCPA-(HPR-Ser46-P)-HPrK/P轴在主要的革兰氏阳性细菌中高度保守，这意味着拟议中的研究的成功完成可能会对疾病的发病机制产生新的见解，与广泛的病原菌相关。这些信息可以成为开发新的治疗或预防干预措施的基础。

DESCRIPTION (provided by applicant): Infections by Gram-positive bacteria cause tens of thousands of deaths in the United States each year. The transcriptional regulator catabolite control protein A (CcpA) has recently been found to influence the virulence gene expression profile during growth in standard laboratory medium of numerous Gram-positive pathogens including group A Streptococcus (GAS). CcpA was originally identified in Bacillus species where it binds DNA sequences termed catabolite response element (cre) sites in conjunction with its co-factor histidine-containing phosphoprotein phosphorylated at serine residue 46 (HPr-Ser46-P). Orthologues of CcpA, HPr, and the kinase/phosphorylase that regulates HPr phosphorlyation status (HPrK/P) are present in all major Gram- positive human pathogens, and there are accumulating data suggesting that the CcpA-(HPr-Ser46-P)-HPrK/P axis contributes to the infectivity of diverse bacterial species. The long term goals of this project are to clearly define how the CcpA-(HPr-Ser46-P)-HPrK/P axis contributes to GAS virulence and to ascertain mechanisms by which CcpA influences gene expression during infection. The specific aims of this proposal have been designed to test hypotheses arising from preliminary data demonstrating that: 1) Inactivation of CcpA altered GAS gene expression during infection in mouse muscle; 2) Inactivation of CcpA decreased GAS virulence in a mouse myositis model; 3) Mutation of the central CpG of a GAS cre site decreased CcpA-(HPr-Ser46-P) DNA binding affinity; and 4) CcpA influenced gene expression under conditions in which HPr-Ser46-P levels are low or absent. In aim 1, gene expression analysis of wild-type and CcpA-inactivated GAS strains will be performed in multiple mouse models of infection to test the hypothesis that CcpA is a key virulence factor regulator during GAS infection. In aim 2, the virulence of CcpA isogenic mutant strains derived from different M protein serotype parental strains will be compared to their parental wild-type strains in various mouse models of infection to test the hypothesis that CcpA positively contributes to the infectivity of GAS strains of multiple M protein serotypes. In aim 3, a combination of in vitro and in vivo methods will be used to test the hypothesis that the central cre site CpG is critical for the effect of CcpA on GAS gene expression. In aim 4, the gene expression profiles of CcpA and HPr-Ser46-P inactivated strains will be compared under different metabolic conditions to test the hypothesis that CcpA can affect GAS gene expression in the absence of HPr-Ser46-P. The highly conserved nature of the CcpA-(HPr-Ser46-P)-HPrK/P axis amongst major Gram-positive bacterial pathogens means that the successful completion of the proposed research may generate new insights into disease pathogenesis that are relevant to a broad array of pathogenic bacteria. Such information could form the basis for the development of novel therapeutic or preventive interventions.