Sequence analysis of the gene encoding alternansucrase, a sucrose glucosyltransferase from Leuconostoc mesenteroides NRRL B-1355

The gene encoding alternansucrase (ASR) from Leuconostoc mesenteroides NRRL B-1355, an original sucrose glucosyltransferase (GTF) specific to alternat ing alpha-1,3 and alpha-1,6 glucosidic bond synthesis, was cloned, sequence d and expressed into Escherichia coli. Recombinant enzyme catalyzed oligoal ternan synthesis from sucrose and maltose acceptor. From sequence compariso n, it appears that ASR possesses the same domains as those described for GT Fs specific to either contiguous alpha-1,3 osidic bond or contiguous alpha- 1,6 osidic bond synthesis. However, the variable region and the glucan bind ing domain are longer than in other GTFs (by 100 and 200 amino acids respec tively). The N-catalytic domain which presents 49% identity with the other GTFs from L. mesenteroides possesses the three determinants potentially inv olved in the glucosyl enzyme formation. (C) 2000 Federation of European Mic robiological Societies. Published by Elsevier Science B.V. All rights reser ved.