DNA-SEQUENCE OF THE GLUCOSYLTRANSFERASE GENE OF SEROTYPE-D STREPTOCOCCUS-SOBRINUS

A glucosyltransferase (GTF) gene was cloned into Escherichia coli from serotype d Stretptococcus sobrinus OMZ176. Transformed E. coli strain MI expressed water-insoluble glucan synthesizing activity. Restrictio n enzyme map of pGT31 extracted from MI shows that the enzyme gene exi sts in the 6.4-kb PstI-fragment inserted into pBR322 vector. DNA seque nce analysis indicates that a single ORF (530 similar to 5,300) is loc ated in the PstI-fragment. The putative amino-acid composition (1,590 residues) resembles those of other GTF-I enzymes obtained from serotyp e g S. sobrinus and serotype h Streptococcus downei. However, at the s ame positions of the sequence, 18 and 142 amino-acid residues are diff erent between serotype d and g, and serotype d and h GTF-I enzymes, re spectively. The differences between serotype d and h GTF-Is are distri buted in N and C-terminal regions.