Extracellular monoenzyme deglycosylation system of 7-O-linked flavonoid beta-rutinosides and its disaccharide transglycosylation activity from Stilbella fimetaria.
We screened for microorganisms able to use flavonoids as a carbon source; and one isolate, nominated Stilbella fimetaria SES201, was found to possess a disaccharide-specific hydrolase. It was a cell-bound ectoenzyme that was released to the medium during conidiogenesis. The enzyme was shown to cleave the flavonoid hesperidin (hesperetin 7-O-alpha-rhamnopyranosyl-beta-glucopyranoside) into rutinose (alpha-rhamnopyranosyl-beta-glucopyranose) and hesperetin. Since only intracellular traces of monoglycosidase activities (beta-glucosidase, alpha-rhamnosidase) were produced, the disaccharidase alpha-rhamnosyl-beta-glucosidase was the main system utilized by the microorganism for hesperidin hydrolysis. The enzyme was a glycoprotein with a molecular weight of 42224 Da and isoelectric point of 5.7. Even when maximum activity was found at 70 degrees C, it was active at temperatures as low as 5 degrees C, consistent with the psychrotolerant character of S. fimetaria. Substrate preference studies indicated that the enzyme exhibits high specificity toward 7-O-linked flavonoid beta-rutinosides. It did not act on flavonoid 3-O-beta-rutinoside and 7-O-beta-neohesperidosides, neither monoglycosylated substrates. In an aqueous medium, the alpha-rhamnosyl-beta-glucosidase was also able to transfer rutinose to other acceptors besides water, indicating its potential as biocatalyst for organic synthesis. The monoenzyme strategy of Acremonium sp. SES201 = DSM 24697, [corrected] as well as the enzyme substrate preference for 7-O-beta-flavonoid rutinosides, is unique characteristics among the microbial flavonoid deglycosylation systems reported.
Mazzaferro
Laura
L
Departamento de Química, Universidad Nacional de La Pampa, Santa Rosa, La Pampa, Argentina.
Piñuel
Lucrecia
L
Minig
Marisol
M
Breccia
Javier D
JD
D004271:DNA, Fungal / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D004187:Disaccharides / Q000378:metabolism*; D004795:Enzyme Stability; D005656:Fungal Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D020459:Genes, rRNA; D005959:Glucosidases / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D006569:Hesperidin / Q000378:metabolism*; D006999:Hypocreales / Q000145:classification / Q000201:enzymology* / Q000254:growth & development / Q000378:metabolism*; D007526:Isoelectric Point; D008969:Molecular Sequence Data; D008970:Molecular Weight; D012331:RNA, Fungal / Q000235:genetics; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D017422:Sequence Analysis, DNA; D013379:Substrate Specificity; D013696:Temperature
D004271:DNA, Fungal; D004275:DNA, Ribosomal; D004187:Disaccharides; D005656:Fungal Proteins; D012331:RNA, Fungal; D012337:RNA, Ribosomal, 18S; C539209:rutinose; D006569:Hesperidin; D005959:Glucosidases; C013015:hesperetin