GENOME SEQUENCE OF STREPTOCOCCUS SOBRINUS

该项目的目标是确定sobrinus链球菌6715的基因组序列，这是一种与龋齿形成有关的口腔细菌。sobrinus链球菌是早期定植的口腔细菌之一，在粘附牙齿表面方面起着重要作用，也与其他类型的细菌聚集形成牙菌斑。与覆盖牙齿表面的宿主衍生蛋白层结合，允许S. sobrinus和相关链球菌开始在口腔定植。S. sobrinus的高酸性使其在环境pH值降低时仍能继续产酸。由于酸的产生对牙釉质中磷酸钙的释放和龋齿的形成至关重要，因此s.s sobrinus继续降低环境pH值的独特能力对全面了解牙周病具有重要意义。随着全基因组测序技术的发展，目前已经可以获得S. sobrinus 6715基因组2.20 Mbp的全基因组序列。完整的序列以及一组互补的克隆将为了解S. sobrinus的生物学提供巨大的资源。拟建项目将包括：i)构建S. sobrinus 6715的随机中小型插入质粒文库和大型插入BAC文库；Ii)约21,333个中小型插入克隆的两端测序；iii)对一组BAC克隆的末端进行测序，以提供基因组支架来排序contigs，并减少缺口闭合所需的工作量；iv)基于数据库相似度搜索，对基因组进行组装和注释，以识别结构特征，并将基因功能角色分配给开放阅读框。这个全基因组测序项目将补充正在进行的相关链球菌的测序和分析，肺炎链球菌、化脓性链球菌、无乳链球菌和变形链球菌，并将允许鉴定这些生物体特有的因素。该项目还将允许了解s.s sobrinus用于成功定植口腔的致病机制。该项目产生的数据将存入公共数据库，包括老虎遗传资源全球网站。此外，用于生成完整基因组序列的文库和重叠BAC克隆集将提供给研究界。

The goal of this project is to determine the genome sequence of Streptococcus sobrinus 6715, an oral bacterium associated with the formation of dental caries. Streptococcus sobrinus is one of the early colonizing oral bacteria that play a significant role in adherence to the tooth surface, and also in coaggregations with other types of bacteria to form plaque. Binding to the host derived protein layer that covers the tooth surface allows S. sobrinus and related streptococci to inititate colonization of the oral cavity. The highly aciduronic nature of S. sobrinus allows the organism to continue producing acid as the pH in its environment lowers. As acid production is important to the release of calcium phosphates from the tooth enamel, and the subsequent formation of caries, this unique ability of S. sobrinus to continue reducing environmental pH is significant to a complete understanding of periodontal disease. Recent advances in whole genome sequencing now make it possible to obtain the complete genome sequence of the 2.20 Mbp genome of S. sobrinus 6715. The complete sequence along with a complementary set of clones will provide a tremendous resource in being able to understand the biology of S. sobrinus. The proposed project will encompass: i) construction of random small and medium insert plasmid libraries and a large insert BAC library from S. sobrinus 6715; ii) sequencing of both ends of approximately 21,333 small and medium insert clones; iii) sequencing the ends of a set of BAC clones clones to provide a genome scaffold to order contigs, and reduce the effort needed for gap closure; and iv) assembly and annotation of the genome to identify structural features, and assign gene functional roles to open reading frames, based on database similarity searches. This whole genome sequencing project will complement the ongoing sequencing and analysis of the related streptococci Streptococcus pneumoniae, S. pyogenes, S. agalactiae, and S. mutans, and will allow for the identification of factors unique to these organisms. The project will also allow for the understanding of the pathogenic mechanisms used by S. sobrinus to successfully colonize the oral cavity. The data generated from this project will be deposited in public databases, including the TIGR World Wide Web Site. In addition, the libraries and overlapping BAC clone sets used to generate the complete genome sequence will be made available to the research community.