A mutant strain of Leuconostoc mesenteroides B-1355 producing a glucosyltransferase synthesizing α(1→2) glucosidic linkages |
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Authors: | M R Smith J C Zahnley R Y Wong R E Lundin J A Ahlgren |
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Institution: | (1) Western Regional Research Center, US Department of Agriculture, 800 Buchanan St, Albany, CA 94710, USA, US;(2) National Center for Agricultural Utilization Research, Biopolymer Unit, US Department of Agriculture, 1815 N University Street, Peoria, IL 61604–3999, USA, US |
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Abstract: | A mutant strain (R1510) of Leuconostoc mesenteroides B-1355 was isolated which synthesized primarily an insoluble polysaccharide and little soluble polysaccharide when grown
in sucrose-containing medium. Glucose or sucrose cultures of this strain produced a single intense band of GTF-1 activity
of 240 kDa on SDS gels, and a number of faint, smaller bands. Oligosaccharides synthesized by strain R1510 from methyl-α-D-glucoside
and sucrose included a trisaccharide whose structure contained an α(1→2) glucosidic linkage. This type of linkage has not
been seen before in any products from strain B-1355 or its mutant derivatives. The structure of the purified trisaccharide
was confirmed by 13C-nuclear magnetic resonance. The insoluble polysaccharide also contained α(1→2) branch linkages, as determined by methylation
analysis, showing that synthesis of the linkages was not peculiar to methyl-α-D-glucoside. GTF-1, which had been excised with
a razor blade from an SDS gel of a culture of the parent strain B-1355, produced the same trisaccharides as strain R1510,
showing that GTF-1 from the wild-type strain was the same as GTF-1 from strain R1510. Mutant strains resembling strain R1510,
but producing a single intense band of alternansucrase (200 kDa) instead of GTF-1 were also isolated, suggesting that mutations
may be generated which diminished the activities for any two of the three GTFs of strain B1355 relative to the third. Strain
R1554 produced a soluble form of alternansucrase, while strain R1588 produced a cell-associated form. The mechanism(s) by
which specific GTFs become associated with the cells of L. mesenteroides was not explored.
Received 12 May 1998/ Accepted in revised form 16 July 1998 |
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Keywords: | : glucosyltransferase dextransucrase alternansucrase Leuconostoc mesenteroides mutant glucan dextran polysaccharide |
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