@entity6586 glucosyltransferases (GTFs; GtfB, -C, and -D) synthesize water-soluble and -insoluble glucan polymers from @entity969 . We have identified previously a conserved region of 19 @entity1522 (aa) (Gtf-P1; aa 409 to 427 of GtfB and aa 435 to 453 of GtfC) which is functionally important for both enzymatic activity and bacterial adherence. Monoclonal antibodies directed against Gtf-P1 selectively inhibited insoluble glucan synthesis by GtfB and -C but had no effect on soluble glucan synthesis by GtfD, suggesting that despite an apparent near identity of sequence, corresponding residues may function differently in these enzymes. To test this hypothesis, we used different strategies of mutagenesis to analyze @entity535 residues of GtfB and GtfC in Gtf-P1. In-frame insertion of 6 @entity1522 preceding, or deletion of 14 @entity1522 within, this conserved region abolished the enzymatic activities of both GtfB and GtfC. Substitution of several residues in combination by random mutagenesis resulted in GtfB, but not GtfC, enzymes exhibiting decreased glucan synthesis and reduced rates of @entity969 hydrolysis. @entity535 substitutions of @entity2574 residues in GtfB or GtfC were found to be more critical for enzymatic activity than at other positions of this region. Interestingly, single mutation at @entity2574 411 or @entity2574 413 of GtfB resulted in enzymes retaining about 20% of wild-type activity, whereas mutagenesis of the corresponding @entity2574 at position 437 or 439 in GtfC resulted in complete loss of enzymatic activity. Furthermore, single @entity535 substitution of a @entity2596 residue between the two @entity2574 residues enhanced the sucrase- and glucan-synthesizing activities of GtfB and GtfC. These results confirmed the report from another laboratory that @entity2574 residues in the Gtf-P1 region are essential for enzymatic catalysis and provide new evidence that identical residues may function differently in closely related Gtf enzymes.

Functional analyses of a conserved region in glucosyltransferases of XXXX .

@entity6586 :: ('1309', 'Species') :: ['Streptococcus mutans'] @entity1522 :: ('CHEBI:33709', 'Chemical') :: ['amino acids'] @entity535 :: ('CHEBI:33704', 'Chemical') :: ['amino acid', 'Amino acid'] @entity969 :: ('MESH:D013395', 'Chemical') :: ['sucrose'] @entity2596 :: ('CHEBI:16414', 'Chemical') :: ['Val'] @entity2574 :: ('CHEBI:22660', 'Chemical') :: ['Asp']
@entity6586 :: (1309,Species) :: ['Streptococcus mutans']
