Sequence and phylogenetic analyses of the water-soluble glucan synthesizing-glucosyltransferase genes of Streptococcus dentirousetti

Two tandemly aligned glucosyltransferase (GTF) genes whose gene products are responsible for water-soluble glucan synthesis were isolated from Streptococcus dentirousetti NUM1303 and sequenced. One of the GTF genes of S. dentirousetti consisted of a 4110 bp open reading frame (ORF) that encoded for a 1369 amino acid protein and was revealed to be a S. sobrinus gtfS homolog. The percent similarity of amino acid sequences of the GTF-S from S. dentirousetti compared to those from S. sobrinus was 99%. In addition, a putative gtfT was found in tandem in the downstream region of the S. dentirousetti gtfS. The gtfT of S. dentirousetti consisted of a 4527 bp ORF encoding for 1508 amino acids. The similarity of amino acid sequences of the GTF-T from S. dentirousetti and S. sobrinus was 94%. Phylogenetic analysis based on amino acid sequences from other related streptococcal GTFs suggested that both GTF-S and GTF-T of S. dentirousetti are closely related to S. sobrinus.