BBB : Vol. 64 (2000) , No. 1 pp.29-38

Gene Encoding a Dextransucrase-like Protein in Leuconostoc mesenteroides NRRL B-512F

Kazumi FUNANE¹⁾, Kouichi MIZUNO¹⁾, Hidenari TAKAHARA²⁾ and Mikihiko KOBAYASHI³⁾

1) Carbohydrate Science Laboratory, National Food Research Institute, Ministry of Agriculture, Forestry and Fisheries
2) Department of Resource Biology, Faculty of Agriculture, Ibaraki University
3) Akita Research Institute of Food and Brewing

(Received June 29, 1999)
(Accepted August 23, 1999)

A gene, dsrT, encoding a dextransucrase-like protein was isolated from the genomic DNA libraries of Leuconostoc mesenteroides NRRL B-512F dextransucrase-like gene. The gene was similar to the intact open reading frames of the dextransucrase gene dsrS of L. mesenteroides NRRL B-512F, dextransucrase genes of strain NRRL B-1299 and streptococcal glucosyltransferase genes, but was truncated after the catalytic domain, apparently by the deletion of five nucleotides. dsrT mRNA was produced in this strain L. mesenteroides when cells were grown in a sucrose medum, but at a level of 20% of that of dsrS mRNA. The molecular weight of the dsrT gene product was 150,000 by SDS-PAGE. The product did not synthesize dextran, but had weak sucrose cleaving activity. The insertion of five nucleotides at the putative deletion point in dsrT resulted in an enzyme with a molecular weight of 210,000 and with dextransucrase activity.

Key words:

dextransucrase; glucosyltransferase; dextran; Leuconostoc mesenteroides