Institute of BioMedical Informatics, National Yang-Ming University, Taipei, Taiwan.
PLoS One. 2011;6(5):e20519. doi: 10.1371/journal.pone.0020519. Epub 2011 May 25.
Streptococcus gallolyticus infections in humans are often associated with bacteremia, infective endocarditis and colon cancers. The disease manifestations are different depending on the subspecies of S. gallolyticus causing the infection. Here, we present the complete genomes of S. gallolyticus ATCC 43143 (biotype I) and S. pasteurianus ATCC 43144 (biotype II.2). The genomic differences between the two biotypes were characterized with comparative genomic analyses. The chromosome of ATCC 43143 and ATCC 43144 are 2,36 and 2,10 Mb in length and encode 2246 and 1869 CDS respectively. The organization and genomic contents of both genomes were most similar to the recently published S. gallolyticus UCN34, where 2073 (92%) and 1607 (86%) of the ATCC 43143 and ATCC 43144 CDS were conserved in UCN34 respectively. There are around 600 CDS conserved in all Streptococcus genomes, indicating the Streptococcus genus has a small core-genome (constitute around 30% of total CDS) and substantial evolutionary plasticity. We identified eight and five regions of genome plasticity in ATCC 43143 and ATCC 43144 respectively. Within these regions, several proteins were recognized to contribute to the fitness and virulence of each of the two subspecies. We have also predicted putative cell-surface associated proteins that could play a role in adherence to host tissues, leading to persistent infections causing sub-acute and chronic diseases in humans. This study showed evidence that the S. gallolyticus still possesses genes making it suitable in a rumen environment, whereas the ability for S. pasteurianus to live in rumen is reduced. The genome heterogeneity and genetic diversity among the two biotypes, especially membrane and lipoproteins, most likely contribute to the differences in the pathogenesis of the two S. gallolyticus biotypes and the type of disease an infected patient eventually develops.
人源型无乳链球菌感染通常与菌血症、感染性心内膜炎和结肠癌相关。不同亚种的无乳链球菌引起的疾病表现不同。本文呈现了无乳链球菌 ATCC 43143（生物型 I）和 S. pasteurianus ATCC 43144（生物型 II.2）的全基因组序列。通过比较基因组分析，对两种生物型的基因组差异进行了特征描述。ATCC 43143 和 ATCC 43144 的染色体分别长 2360 和 2100Mb，分别编码 2246 和 1869 个 CDS。两个基因组的组织结构和基因组内容与最近发表的无乳链球菌 UCN34 最为相似，其中 ATCC 43143 和 ATCC 43144 的 2073（92%）和 1607（86%）个 CDS 在 UCN34 中被保守保留。在所有链球菌基因组中约有 600 个 CDS 被保守保留，表明链球菌属具有较小的核心基因组（占总 CDS 的约 30%）和较大的进化可塑性。我们分别在 ATCC 43143 和 ATCC 43144 中鉴定了 8 个和 5 个基因组可塑性区域。在这些区域内，一些蛋白被认为对两种亚种的适应性和毒力有贡献。我们还预测了一些可能与细胞表面相关的蛋白，这些蛋白可能在与宿主组织的黏附中发挥作用，从而导致持续性感染，引起人类亚急性和慢性疾病。本研究表明，无乳链球菌仍然具有适合瘤胃环境的基因，而 S. pasteurianus 适应瘤胃的能力降低。两种生物型之间的基因组异质性和遗传多样性，特别是膜和脂蛋白，很可能导致两种无乳链球菌生物型的发病机制和受感染患者最终发展出的疾病类型存在差异。
