Department of Oral and Craniofacial Sciences, Faculty of Dentistry, University of Malaya, 50603, Kuala Lumpur, Malaysia.
Centre for Oral Health Research, School of Dental Sciences, Newcastle University, Newcastle upon Tyne, NE2 4BW, United Kingdom.
Sci Rep. 2017 Jun 7;7(1):2949. doi: 10.1038/s41598-017-02399-4.
Streptococcus gordonii and Streptococcus sanguinis are pioneer colonizers of dental plaque and important agents of bacterial infective endocarditis (IE). To gain a greater understanding of these two closely related species, we performed comparative analyses on 14 new S. gordonii and 5 S. sanguinis strains using various bioinformatics approaches. We revealed S. gordonii and S. sanguinis harbor open pan-genomes and share generally high sequence homology and number of core genes including virulence genes. However, we observed subtle differences in genomic islands and prophages between the species. Comparative pathogenomics analysis identified S. sanguinis strains have genes encoding IgA proteases, mitogenic factor deoxyribonucleases, nickel/cobalt uptake and cobalamin biosynthesis. On the contrary, genomic islands of S. gordonii strains contain additional copies of comCDE quorum-sensing system components involved in genetic competence. Two distinct polysaccharide locus architectures were identified, one of which was exclusively present in S. gordonii strains. The first evidence of genes encoding the CylA and CylB system by the α-haemolytic S. gordonii is presented. This study provides new insights into the genetic distinctions between S. gordonii and S. sanguinis, which yields understanding of tooth surfaces colonization and contributions to dental plaque formation, as well as their potential roles in the pathogenesis of IE.
戈登链球菌和血链球菌是牙菌斑的先驱定植者，也是细菌性感染性心内膜炎（IE）的重要病原体。为了更深入地了解这两种密切相关的物种，我们使用各种生物信息学方法对 14 株新的戈登链球菌和 5 株血链球菌菌株进行了比较分析。结果表明，戈登链球菌和血链球菌拥有开放的泛基因组，具有高度的序列同源性和核心基因（包括毒力基因）数量。然而，我们观察到它们在基因组岛和前噬菌体方面存在细微差异。比较病原体基因组学分析鉴定出血链球菌菌株具有编码 IgA 蛋白酶、有丝分裂因子脱氧核糖核酸酶、镍/钴摄取和钴胺素生物合成的基因。相反，戈登链球菌菌株的基因组岛包含与遗传能力有关的 comCDE 群体感应系统成分的额外拷贝。我们鉴定出两种截然不同的多糖基因座结构，其中一种仅存在于戈登链球菌菌株中。首次在 α-溶血性戈登链球菌中发现了编码 CylA 和 CylB 系统的基因。本研究为戈登链球菌和血链球菌之间的遗传差异提供了新的见解，有助于了解牙齿表面的定植和对牙菌斑形成的贡献，以及它们在 IE 发病机制中的潜在作用。
