Reaction: Cyclizes part of a (1→2)-β-D-glucan chain by formation of a (1→2)-β-D-glucosidic bond
Systematic name: (1→2)-β-D-glucan:(1→2)-β-D-glucan 2-β-D-[(1→2)-β-D-glucano]-transferase (cyclizing and configuration-retaining)
Comments: This enzyme is the cyclization domain of cyclic β-1,2-glucan synthase. Enzymes from Brucella abortus and Thermoanaerobacter italicus were characterized. The cyclization domain of cyclic β-1,2-glucan synthase is flanked by an N-terminal β-1,2-glucosyltransferase domain (cf. EC 2.4.1.391) and a C-terminal β-1,2-glucoside phosphorylase domain (cf. EC 2.4.1.333), with the former responsible for elongation and the latter for chain length control. The cyclization domain of Thermoanaerobacter italicus cyclizes linear oligosaccharides with a degree of polymerization (DP) of 21 or higher to produce cyclic glucans with DP 17 or higher. The cyclization domain also disproportionates linear β-1,2-glucooligosaccharides without cycling. The entire cyclic β-1,2-glucan synthase from Brucella abortus synthesizes cyclic β-1,2-glucans with DP 17-22.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:
References:
1. Inon de Iannino, N., Briones, G., Tolmasky, M. and Ugalde, R.A. Molecular cloning and characterization of cgs, the Brucella abortus cyclic β(1-2) glucan synthetase gene: genetic complementation of Rhizobium meliloti ndvB and Agrobacterium tumefaciens chvB mutants. J. Bacteriol. 180 (1998) 4392-4400. [PMID: 9721274]
2. Guidolin, L.S., Ciocchini, A.E., Inon de Iannino, N. and Ugalde, R.A. Functional mapping of Brucella abortus cyclic β-1,2-glucan synthase: identification of the protein domain required for cyclization. J. Bacteriol. 191 (2009) 1230-1238. [PMID: 19074375]
3. Guidolin, L.S., Morrone Seijo, S.M., Guaimas, F.F., Comerci, D.J. and Ciocchini, A.E. Interaction network and localization of Brucella abortus membrane proteins involved in the synthesis, transport, and succinylation of cyclic β-1,2-glucans. J. Bacteriol. 197 (2015) 1640-1648. [PMID: 25733613]
4. Tanaka, N., Saito, R., Kobayashi, K., Nakai, H., Kamo, S., Kuramochi, K., Taguchi, H., Nakajima, M. and Masaike, T. Functional and structural analysis of a cyclization domain in a cyclic β-1,2-glucan synthase. Appl. Microbiol. Biotechnol. 108 (2024) 187. [PMID: 38300345]