Oral and Maxillofacial Pathology, School of Clinical Dentistry, Claremont Crescent, University of Sheffield, S102TA Sheffield, United Kingdom.
J Bacteriol. 2010 May;192(9):2285-93. doi: 10.1128/JB.00079-10. Epub 2010 Feb 26.
Tannerella forsythia is a key contributor to periodontitis, but little is known of its virulence mechanisms. In this study we have investigated the role of sialic acid in biofilm growth of this periodontal pathogen. Our data show that biofilm growth of T. forsythia is stimulated by sialic acid, glycolyl sialic acid, and sialyllactose, all three of which are common sugar moieties on a range of important host glycoproteins. We have also established that growth on sialyllactose is dependent on the sialidase of T. forsythia since the sialidase inhibitor oseltamivir suppresses growth on sialyllactose. The genome of T. forsythia contains a sialic acid utilization locus, which also encodes a putative inner membrane sialic acid permease (NanT), and we have shown this is functional when it is expressed in Escherichia coli. This genomic locus also contains a putatively novel TonB-dependent outer membrane sialic acid transport system (TF0033-TF0034). In complementation studies using an Escherichia coli strain devoid of its outer membrane sialic acid transporters, the cloning and expression of the TF0033-TF0034 genes enabled an E. coli nanR nanC ompR strain to utilize sialic acid as the sole carbon and energy source. We have thus identified a novel sialic acid uptake system that couples an inner membrane permease with a TonB-dependent outer membrane transporter, and we propose to rename these novel sialic acid uptake genes nanO and nanU, respectively. Taken together, these data indicate that sialic acid is a key growth factor for this little-characterized oral pathogen and may be key to its physiology in vivo.
福赛拟杆菌是牙周炎的主要病原体，但人们对其毒力机制知之甚少。在这项研究中，我们研究了唾液酸在这种牙周病原体生物膜生长中的作用。我们的数据表明，唾液酸、乙醯神经氨酸和唾液乳糖都能刺激福赛拟杆菌的生物膜生长，这三种物质都是多种重要宿主糖蛋白上常见的糖基。我们还确定了福赛拟杆菌在唾液乳糖上的生长依赖于其唾液酸酶，因为唾液酸酶抑制剂奥司他韦能抑制唾液乳糖上的生长。福赛拟杆菌的基因组包含一个唾液酸利用基因座，该基因座还编码一个假定的内膜唾液酸渗透酶（NanT），当它在大肠杆菌中表达时，我们已经证明了它是有功能的。这个基因组座还包含一个假定的新型 TonB 依赖性外膜唾液酸转运系统（TF0033-TF0034）。在使用缺乏外膜唾液酸转运蛋白的大肠杆菌菌株进行的互补研究中，克隆和表达 TF0033-TF0034 基因使大肠杆菌 nanR nanC ompR 菌株能够利用唾液酸作为唯一的碳源和能源。因此，我们鉴定了一种新型的唾液酸摄取系统，该系统将内膜渗透酶与 TonB 依赖性外膜转运蛋白偶联，我们建议分别将这些新的唾液酸摄取基因命名为 nanO 和 nanU。总之，这些数据表明，唾液酸是这种研究较少的口腔病原体的关键生长因子，可能是其体内生理学的关键。
