Amylase binding and gene expression in S. gordonii

描述(申请人提供)：众所周知，唾液成分可以与微生物相互作用，影响它们在口腔中的定植。一种这样的交互涉及 丰富的唾液酶，淀粉酶，它与共生口腔链球菌特异结合，具有高亲和力，是唾液涂层牙齿的早期定居者，在牙龈上菌斑中大量存在。淀粉酶结合链球菌(ABS)只在具有唾液淀粉酶活性的宿主上定植，这表明淀粉酶相互作用调节ABS的口腔定植，并具有进化基础。戈登链球菌产生两种淀粉酶结合蛋白[ABPA(20-kDa)和AbpB(82-kDa)]。淀粉酶与该物种的结合仅依赖于戈登链霉菌中的ABPA(以及可能在其他物种中的同源物)，而不依赖于AbpB。体外研究发现，ABPs在细菌黏附和生物膜形成中发挥作用。有趣的是，ABPA缺陷的戈登葡萄球菌突变体能够在大鼠的口腔和亲本菌株中定植，这表明额外的细菌因素参与了在体内的定植和存活。根据这些发现，我们考虑了这些蛋白质潜在的新功能。初步研究表明，淀粉酶与戈登链球菌结合后，可在细菌细胞中诱导差异基因表达。因此，这项建议的具体目标是：1：确定可能参与新的信号通路的与ABPA相互作用的链球菌成分。2：确定ABPA的三维结构，鉴定淀粉酶结合基序，探讨ABP基因序列差异的进化基础。3：比较Gordonii淀粉酶结合后的整体基因表达反应与全唾液和导管唾液以及其他纯化唾液成分(如粘蛋白、SIgA等)结合后的反应。唾液介导的细菌信号通路的知识可能会有临床应用，例如通过设计类似药物作为微生物定植的抑制剂或促进剂。这类药物可以选择性地操纵细菌的定植，进而影响疾病的预防或控制。这一知识可以很好地扩展到口腔内生物膜的发育，并应用于影响全身疾病的其他微生物群落。 与公共健康相关：唾液的成分被认为有助于牙菌斑的形成，牙菌斑是牙齿上形成的生物膜，会导致龋齿和牙周病。这项提案将讨论唾液中丰富的淀粉酶与一种常见的口腔有机体戈登链球菌相互作用的机制以及这种相互作用的功能的细节。对这种相互作用的了解可能会导致控制牙菌斑形成的新策略，从而预防口腔疾病。

DESCRIPTION (provided by applicant): It is well known that salivary components can interact with microbes to influence their colonization of the oral cavity. One such interaction involves the abundant salivary enzyme, amylase, which binds specifically and with high affinity to commensal oral streptococci that are early colonizers of the saliva-coated tooth and numerous in supragingival dental plaque. Amylase-binding streptococci (ABS) colonize only hosts with detectable salivary amylase activity suggesting that amylase interactions modulate oral colonization by ABS and have an evolutionary basis. The ABS S. gordonii produces two amylase-binding proteins (ABPs) [AbpA (20-kDa) and AbpB (82-kDa) of Streptococcus gordonii. The binding of amylase to this species is dependent only on AbpA in S. gordonii (and likely its homologs in other species), and not on AbpB. In vitro studies found ABPs to play a role in bacterial adhesion and biofilm formation. Interestingly, AbpA defective S. gordonii mutants were able to colonize rat mouths as well as the parental strains, suggesting that additional bacterial factors are involved in colonization and survival in vivo. In light of these findings, we have considered potentially novel functions for these proteins. Preliminary studies suggest that amylase-binding to S. gordonii elicits differential gene expression in the bacterial cell. Thus, th Specific Aims of this proposal are to: 1: identify streptococcal components that interact with AbpA that may participate in a novel signaling pathway. 2: determine the three-dimensional structure of AbpA, identify amylase binding motifs and to address the evolutionary basis for the divergence of ABP gene sequence. 3: compare the global gene expression response of S. gordonii following binding of amylase to the response induced by the binding of whole- and ductal-saliva and other purified salivary components (such as mucins, sIgA, etc). Knowledge of saliva-mediated bacterial signaling pathways could have clinical application, for example by devising analog agents that serve as inhibitors or promoters of microbial colonization. Such agents may enable selective manipulation of bacterial colonization, and by extension, impact disease prevention or control. This knowledge could well extend beyond biofilm development in the oral cavity, with application to other microbial communities affecting systemic disease. PUBLIC HEALTH RELEVANCE: Components of saliva are thought to contribute to the formation of dental plaque, the biofilm that forms on teeth that causes dental decay and gum disease. This proposal will address details of the mechanism by which an abundant enzyme in saliva, amylase, interacts with a common oral organism, Streptococcus gordonii and the function of this interaction. Understanding of this interaction could lead to new strategies to control dental plaque formation and thus prevent oral disease.