Functional, genetic, and bioinformatic characterization of dextransucrase (DSRBCB4) gene in Leuconostoc mesenteroides B-1299CB4.
A gene encoding a dextransucrase (dsrBCB4) that synthesizes only alpha-1,6-linked dextran was cloned from Leuconostoc mesenteroides B-1299CB4. The coding region consisted of an open reading frame (ORF) of 4,395 bp that coded a 1,465-amino-acids protein with a molecular mass 163,581 Da. The expressed recombinant DSRBCB4 (rDSRBCB4) synthesized oligosaccharides in the presence maltose or isomaltose as an acceptor, plus the products included alpha-1,6-linked glucosyl residues in addition to the maltosyl or isomaltosyl residue. Alignments of the amino acid sequence of DSRBCB4 with glucansucrases from Streptococcus and Leuconostoc identified conserved amino acid residues in the catalytic core that are critical for enzyme activity. The mutants D530N, E568Q, and D641N displayed a 98- to 10,000-fold reduction of total enzyme activity.
Kang
Hee-Kyoung
HK
School of Biological Sciences and Technology, Chonnam National University, Gwang-ju, Korea.
Kim
Young-Min
YM
Kim
Do-Man
DM
D000595:Amino Acid Sequence; D001483:Base Sequence; D020134:Catalytic Domain / Q000235:genetics; D003001:Cloning, Molecular; D019295:Computational Biology; D004269:DNA, Bacterial / Q000235:genetics; D003911:Dextrans / Q000096:biosynthesis; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D005798:Genes, Bacterial; D005964:Glucosyltransferases / Q000235:genetics* / Q000378:metabolism; D007934:Leuconostoc / Q000201:enzymology* / Q000235:genetics*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011994:Recombinant Proteins / Q000235:genetics; D016415:Sequence Alignment; D013395:Sucrose / Q000378:metabolism
D004269:DNA, Bacterial; D003911:Dextrans; D011994:Recombinant Proteins; D013395:Sucrose; D005964:Glucosyltransferases; C020025:dextransucrase