Analysis of the Streptococcus downei gtfS gene, which specifies a glucosyltransferase that synthesizes soluble glucans.
The complete nucleotide sequence was determined for the Streptococcus downei (previously Streptococcus sobrinus) MFe28 gtfS gene which specifies a glucosyltransferase (GTF-S) producing water-soluble glucan. A single open reading frame which encodes a mature protein with a molecular weight of 147,408 (1,328 amino acids) and a putative signal peptide 36 or 37 amino acids in length was detected. GTF-S shares extensive sequence similarity with GTF-I (gtfI) from S. downei and GTF-I (gtfB) and GTF-SI (gtfC) from Streptococcus mutans. GTF-S contains a highly conserved enzymatic domain and C-terminal repeated sequences which appear to be involved in glucan binding. Comparison of the deduced GTF-S protein sequence with other sequenced GTF genes of mutans streptococci revealed that these C-terminal repeats occurred in all cases, although the patterns of repeated sequences varied with respect to each other and to the glucan-binding protein of S. mutans. GTF-S contains four C-terminal repeat sequences ranging from 49 to 51 amino acids in length and a partial repeat of 13 amino acids. Nuclear magnetic resonance analysis of the glucan produced by GTF-S revealed that the product consisted of more than 90% alpha-1,6-linked glucosyl residues.
Gilmore
K S
KS
Department of Microbiology & Immunology, University of Oklahoma Health Sciences Center, Oklahoma City 73190.
Russell
R R
RR
Ferretti
J J
JJ
D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D004269:DNA, Bacterial; D005798:Genes, Bacterial; D005936:Glucans / Q000096:biosynthesis*; D005964:Glucosyltransferases / Q000235:genetics*; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D012689:Sequence Homology, Nucleic Acid; D013291:Streptococcus / Q000201:enzymology / Q000235:genetics*; D013295:Streptococcus mutans / Q000235:genetics; D013395:Sucrose / Q000378:metabolism
D004269:DNA, Bacterial; D005936:Glucans; D013395:Sucrose; D005964:Glucosyltransferases