Transferases;
Glycosyltransferases;
Hexosyltransferases

sucrose:(1->6)-alpha-D-glucan 3(6)-alpha-D-glucosyltransferase

(1) sucrose + [(1->6)-alpha-D-glucosyl]n = D-fructose + [(1->6)-alpha-D-glucosyl]n+1  [RN:R02120 R06066];
(2) sucrose + [(1->6)-alpha-D-glucosyl]n = D-fructose + (1->3)-alpha-D-glucosyl-[(1->6)-alpha-D-glucosyl]n

R02120 R06066(G)

sucrose [CPD:C00089];
[(1->6)-alpha-D-glucosyl]n

The glucansucrases transfer a D-glucosyl residue from sucrose to a glucan chain. They are classified based on the linkage by which they attach the transferred residue. In some cases, in which the enzyme forms more than one linkage type, classification relies on the relative proportion of the linkages that are generated. Currently classified glucansucrases include EC 2.4.1.372, mutansucrase, which extends (1->3)-alpha-D-glucans; EC 2.4.1.4, amylosucrase, which extends (1->4)-alpha-D-glucans; EC 2.4.1.5, dextransucrase, which extends (1->6) alpha-D-glucans; EC 2.4.1.373, alpha-(1->2) branching sucrase, which introduces alpha(1->2) branches into (1->6)-alpha-D-glucans; EC 2.4.1.125, sucrose---1,6-alpha-glucan 3(6)-alpha-glucosyltransferase, which extends (1->6) alpha-D-glucans by both alpha(1->3) and alpha(1->6) linkages, with one of the linkage types being dominant; and EC 2.4.1.140, alternansucrase, which forms both alpha(1->3) and alpha(1->6) linkages in approximately equal amounts by alternating the linkage type. This enzyme was characterized from the dental caries bacterium Streptococcus mutans. It produces a highly-branched extracellular D-glucan polymers that promote attachment of the bacteria to teeth. Three types of the enzyme have been described; the insoluble polymers produced by GTF-I and GTF-SI contain 85% alpha(1->3) bonds and 15% alpha(1->6) bonds, while the soluble polymers produced by GTF-S contain only 30% of alpha(1->3) bonds and 70% alpha(1->6) bonds.

EC 2.4.1.125 created 1984

1  [PMID:6216919]

Mukasa H, Shimamura A, Tsumori H.

Purification and characterization of basic glucosyltransferase from Streptococcus mutans serotype c.

Biochim Biophys Acta 719:81-9 (1982)
DOI:10.1016/0304-4165(82)90310-5

2  [PMID:6461359]

Shimamura A, Tsumori H, Mukasa H.

Purification and properties of Streptococcus mutans extracellular glucosyltransferase.

Biochim Biophys Acta 702:72-80 (1982)
DOI:10.1016/0167-4838(82)90028-0

3  [PMID:2937877]

Tsumori H, Shimamura A, Mukasa H.

Purification and properties of extracellular glucosyltransferase synthesizing 1,6-, 1,3-alpha-D-glucan from Streptococcus mutans serotype a.

J Gen Microbiol 131:3347-53 (1985)
DOI:10.1099/00221287-131-12-3347

4  [PMID:8737492]

Fujiwara T, Tamesada M, Bian Z, Kawabata S, Kimura S, Hamada S

Deletion and reintroduction of glucosyltransferase genes of Streptococcus mutans  and role of their gene products in sucrose dependent cellular adherence.

Microb Pathog 20:225-33 (1996)
DOI:10.1006/mpat.1996.0021

5  [PMID:10234842]

Monchois V, Willemot RM, Monsan P

Glucansucrases: mechanism of action and structure-function relationships.

FEMS Microbiol Rev 23:131-51 (1999)
DOI:10.1111/j.1574-6976.1999.tb00394.x

6  [PMID:21354427]

Ito K, Ito S, Shimamura T, Weyand S, Kawarasaki Y, Misaka T, Abe K, Kobayashi T, Cameron AD, Iwata S

Crystal structure of glucansucrase from the dental caries pathogen Streptococcus  mutans.

J Mol Biol 408:177-86 (2011)
DOI:10.1016/j.jmb.2011.02.028