The Structural and Functional Determination of Streptococcus mutans Adherence

龋齿是一种影响世界上大部分人口的多种微生物疾病，在那里 合作生态组织的和谐性向非生态化框架转变 致病微生物，尤其是变形链球菌(SM)。对于浮游性SM，粘着到牙齿上 表面和/或牙科生物膜是龋病发病机制中的关键步骤，SM已进化为(I)SM- 宿主和(Ii)SM-微生物的相互作用，这是通过其表面蛋白(粘附素)介导的。 SM的黏附介导的相互作用包括：(A)最近发现冗余的高亲和力结合 SM的粘附素与唾液糖蛋白340(Gp340)的清道夫受体半胱氨酸富集区(SRCR)， 这促进了SM-主机界面上的龋齿易感性；以及(B)SM所需的粘附素的揭示 对于SM-白色念珠菌(CA)生物膜的形成和产酸，增强了早期的致龋性 儿童龋齿在SM-微生物界面。这些共同揭示了以前未知的相互作用。 曾经被认为是SM上广为人知和刻画的粘附素。然而关键的悬而未决的问题 仍然是，“SM是如何调节这种多余的，但与宿主蛋白质和其他微生物的特异性结合的？” 这个应用程序的目标是确定驱动驱动的特定基序(S)和/或分子机制(S SM的粘附性，特别是它们如何实现与多个配体的结合。我们的结构和功能研究 结果表明，SM的表面粘附素主要通过两个主要的结构域，即V- 和C折。我们推测，SM表面粘附素上的V-折叠和C-折叠介导了特异性 通过共同结合基序的相互作用(S)，这些基序对生物膜的形成和微生物定植至关重要“。 我们将通过三个特定目标(SA)来解决我们的假设，方法是：(A)将遵守主题(S)映射到 口服链球菌粘附素的V-折叠(SA1)和(B)C-折叠(SA2)，以及(C)研究SM的粘附素的作用 在SM-白色念珠菌(CA)界面(SA3)。 这项多PD/PI研究的结果将(I)确定全球采用的绑定主题(S)/机制 通过SM的粘附素中的V-折叠和C-折叠；(Ii)确定存在明显的和/或重叠的粘附性 不同配体的结合部位；(3)提供变形菌中各种粘附素的V-折叠和C-折叠的比较分析 和绿色链球菌，揭示其结合基序/机制因物种而异的差异； 表征SM粘附素在SM-CA界面上的作用；以及(V)阐明微生物中的变化 受SM的V-折叠和C-折叠调节的生态，特别是当它们与龋齿有关时。 我们建议的结构分析、关键黏附基序的遗传操作(S)和动物模型研究 将确定黏附机制并解决SM的V-折叠和C-折叠上的知识差距，特别是 它们在促进殖民和毒力方面发挥了关键作用。这一结果将使选择性的未来发展成为可能 组合疗法以防止SM对宿主和微生物的黏附。

Dental caries is a polymicrobial disease that affects much of the human population worldwide, where the harmony of a cooperative eco-organization shifts towards a dysbiotic framework with overrepresentation of pathogenic microorganisms, particularly by Streptococcus mutans (SM). For planktonic SM, adhesion to tooth surface and/or dental biofilms is a crucial step in the pathogenesis of dental caries, and SM has evolved (i) SM- host and (ii) SM-microbial interactions, which are mediated through its surface proteins (adhesins). SM’s adhesion mediated interactions include: (A) The recent discovery of redundant high affinity binding of SM’s adhesins to the scavenger receptor cysteine rich domains (SRCR) of the salivary glycoprotein 340 (Gp340), which promotes caries susceptibility in the SM-host interface; and (B) The revelation of SM’s adhesin required for the SM-Candida albicans (CA) biofilm formation and acid production, which enhances cariogenicity in early childhood caries in the SM-microbial interface. Together these have revealed previously unknown interactions by once thought to be well-known and well-characterized adhesins on SM. Yet the key unanswered question remains, “how does SM mediate such redundant, but specific binding to host proteins and to other microbes?” The goal of this application is to determine the specific motif(s) and/or molecular mechanism(s) that drive SM’s adherence, particularly how they enable binding to multiple ligands. Our structural and functional studies show that SM’s surface adhesins mediate these attachments primarily via two major structural domains, the V- and C-fold. We hypothesize that “the V- and C-fold present on the surface adhesins of SM mediate specific interactions through common binding motif(s) that are crucial for biofilm formation and microbial colonization”. We will address our hypothesis through three specific aims (SAs) by (a) mapping the adherence motif(s) on the V-fold (SA1) and (b) C-fold (SA2) of oral streptococcal adhesins, and (c) investigating the role of SM’s adhesins in the SM-Candida albicans (CA) interface (SA3). The results from this multi-PD/PI study will (i) Determine the binding-motif(s)/mechanisms globally adopted by the V- and C-fold among SM’s adhesins; (ii) Determine the presence of distinct and/or overlapping adherence sites for various ligands; (iii) Provide a comparative analysis of the V- and C-fold of various adhesins from mutans and viridans streptococci, revealing species-specific differences in their binding-motifs/mechanisms; (iv) Characterize the role of SM adhesins at the SM-CA interface; and (v) Elucidate alternations in the microbial ecology modulated by SM’s V- and C-folds, particularly as they relate to dental caries. Our proposed structural analyses, genetic manipulation of key adhesion motif(s) and animal model studies will determine the adherence mechanisms and address the knowledge gap on SM’s V- and C-fold, particularly their crucial role in promoting colonization and virulence. The results will enable future development of selective combinatorial therapeutics to prevent SM’s adherence to host and microbes.