Department of Oral Biology, The State University of New York at Buffalo, New York, USA.
Infect Immun. 2012 Jan;80(1):3-13. doi: 10.1128/IAI.05773-11. Epub 2011 Oct 24.
The oral bacterium Porphyromonas gingivalis is a key etiological agent of human periodontitis, a prevalent chronic disease that affects up to 80% of the adult population worldwide. P. gingivalis exhibits neuraminidase activity. However, the enzyme responsible for this activity, its biochemical features, and its role in the physiology and virulence of P. gingivalis remain elusive. In this report, we found that P. gingivalis encodes a neuraminidase, PG0352 (SiaPg). Transcriptional analysis showed that PG0352 is monocistronic and is regulated by a sigma70-like promoter. Biochemical analyses demonstrated that SiaPg is an exo-α-neuraminidase that cleaves glycosidic-linked sialic acids. Cryoelectron microscopy and tomography analyses revealed that the PG0352 deletion mutant (ΔPG352) failed to produce an intact capsule layer. Compared to the wild type, in vitro studies showed that ΔPG352 formed less biofilm and was less resistant to killing by the host complement. In vivo studies showed that while the wild type caused a spreading type of infection that affected multiple organs and all infected mice were killed, ΔPG352 only caused localized infection and all animals survived. Taken together, these results demonstrate that SiaPg is an important virulence factor that contributes to the biofilm formation, capsule biosynthesis, and pathogenicity of P. gingivalis, and it can potentially serve as a new target for developing therapeutic agents against P. gingivalis infection.
口腔细菌牙龈卟啉单胞菌是人类牙周炎的主要病因之一，牙周炎是一种普遍的慢性疾病，影响全球多达 80%的成年人。牙龈卟啉单胞菌具有神经氨酸酶活性。然而，负责这种活性的酶、其生化特征及其在牙龈卟啉单胞菌生理学和毒力中的作用仍不清楚。在本报告中，我们发现牙龈卟啉单胞菌编码一种神经氨酸酶，PG0352（SiaPg）。转录分析表明，PG0352 是单顺反子，受 sigma70 样启动子调控。生化分析表明，SiaPg 是一种外切-α-神经氨酸酶，可切割糖苷键连接的唾液酸。低温电子显微镜和断层扫描分析显示，PG0352 缺失突变体（ΔPG352）无法产生完整的荚膜层。与野生型相比，体外研究表明，ΔPG352 形成的生物膜较少，对宿主补体杀伤的抵抗力较低。体内研究表明，虽然野生型引起的是一种扩散性感染，会影响多个器官，所有感染的小鼠都会死亡，但ΔPG352 只引起局部感染，所有动物都存活下来。综上所述，这些结果表明 SiaPg 是一种重要的毒力因子，有助于牙龈卟啉单胞菌的生物膜形成、荚膜生物合成和致病性，它可能成为开发针对牙龈卟啉单胞菌感染的治疗药物的新靶标。
