Shinozaki-Kuwahara Noriko, Takada Kazuko, Hirasawa Masatomo
Department of Microbiology and Immunology, Nihon University School of Dentistry at Matsudo, Matsudo, Chiba 271-8587, Japan.
J Microbiol. 2008 Apr;46(2):202-8. doi: 10.1007/s12275-007-0199-z. Epub 2008 Jun 11.
Nucleotide sequences of water-insoluble glucan-producing glucosyltransferase (gtf) genes of new mutans streptococci isolated from pig oral cavity, Streptococcus orisuis JCM14035, and of Streptococcus criceti HS-6 were determined. The gtf gene of S. orisuis JCM14035 consisted of a 4,401 bp ORF encoding for a 1,466 amino acids, and was revealed to belong to the gtfI group. The percent homology of amino acid sequence of the GTF-I from S. orisuis and S. criceti are 95.0%, however, this score ranges from 77.0% to 78.0% when compared to Streptococcus sobrinus 6715. The deduced N-terminal amino acid sequence was considered responsible for the secretion of GTF-I in S. orisuis JCM14035 and S. criceti HS-6 with high similarity to known GTF proteins from other streptococci. In addition, two other conserved regions, i.e., N-terminal putative catalytic-site and C-terminal glucan binding domain, were also found in GTF-Is of S. orisuis JCM14035 and S. criceti HS-6. Phylogenetic analysis suggested that S. orisuis JCM14035 and S. criceti HS-6, closely related to each other, resemble S. sobrinus and S. downei based on the amino acid sequences of the GTFs.
测定了从猪口腔分离出的新型变形链球菌——猪源链球菌JCM14035和仓鼠链球菌HS-6的产水不溶性葡聚糖葡糖基转移酶（gtf）基因的核苷酸序列。猪源链球菌JCM14035的gtf基因由一个4401 bp的开放阅读框组成，编码1466个氨基酸，属于gtfI组。猪源链球菌和仓鼠链球菌的GTF-I氨基酸序列同源性为95.0%，但与远缘链球菌6715相比，该同源性在77.0%至78.0%之间。推导的N端氨基酸序列被认为与猪源链球菌JCM14035和仓鼠链球菌HS-6中GTF-I的分泌有关，与其他链球菌已知的GTF蛋白高度相似。此外，在猪源链球菌JCM14035和仓鼠链球菌HS-6的GTF-I中还发现了另外两个保守区域，即N端假定催化位点和C端葡聚糖结合结构域。系统发育分析表明，基于GTF的氨基酸序列，猪源链球菌JCM14035和仓鼠链球菌HS-6彼此密切相关，与远缘链球菌和唐氏链球菌相似。
