Water-soluble and water-insoluble glucans produced by Escherichia coli recombinant dextransucrases from Leuconostoc mesenteroides NRRL B-512F.
Two dextransucrase genes, dsrS and dsrT5, from Leuconostoc mesenteroides NRRL B-512F were expressed in Escherichia coli, and recombinant dsrT5 dextransucrase was shown to produce a water-insoluble glucan. In contrast, native dextran from L. mesenteroides B-512F is water-soluble. The water-insoluble glucan was shown by 13C NMR and glycosyl-linkage composition analysis to contain about 50% 6-linked Glcp and 40% 3-linked Glcp. The 'primitive' B-512F strain is suggested to have produced water-insoluble glucan containing 3-linked Glcp. The glucans produced by dextransucrases expressed in E. coli contained 4-linked Glcp, as shown by glycosyl-linkage composition analysis. The amount of 4-linked Glcp was increased when the truncated, water-insoluble, glucan-producing dextransucrase, which does not have C-terminal repeating units, was added to the water-soluble, glucan-producing dextransucrase. Trace amounts of 4-linked Glcp were also detected in the dextran obtained from the B-512F culture supernatant, in dextran produced by dextransucrase purified from the B-512F strain culture supernatant, and in clinical dextran. The results of glycosyl-linkage composition analysis suggest that dextransucrases produce 4-linked Glcp as well as 6- and 3-linked Glcp.
Funane
K
K
National Food Research Institute, Ministry of Agriculture, Forestry and Fisheries, 2-1-2 Kannondai, Tsukuba, 305-8642, Ibaraki, Japan. funane@nfri.affrc.go.jp
Ishii
T
T
Matsushita
M
M
Hori
K
K
Mizuno
K
K
Takahara
H
H
Kitamura
Y
Y
Kobayashi
M
M
D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D005798:Genes, Bacterial / Q000235:genetics; D005936:Glucans / Q000737:chemistry* / Q000378:metabolism*; D005964:Glucosyltransferases / Q000235:genetics* / Q000378:metabolism*; D007934:Leuconostoc / Q000201:enzymology* / Q000235:genetics; D019906:Nuclear Magnetic Resonance, Biomolecular; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012995:Solubility; D014867:Water / Q000737:chemistry*
D005936:Glucans; D011994:Recombinant Proteins; D014867:Water; D005964:Glucosyltransferases; C020025:dextransucrase