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The maltodextrin transport system and metabolism in Lactobacillus acidophilus NCFM and production of novel α ‐glucosides through reverse phosphorolysis by maltose phosphorylase
Author(s) -
Nakai Hiroyuki,
Baumann Martin J.,
Petersen Bent O.,
Westphal Yvonne,
Schols Henk,
Dilokpimol Adiphol,
Hachem Maher A.,
Lahtinen Sampo J.,
Duus Jens Ø.,
Svensson Birte
Publication year - 2009
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/j.1742-4658.2009.07445.x
Subject(s) - maltose , chemistry , phosphorolysis , biochemistry , maltodextrin , phosphoglucomutase , mannose , glycogen phosphorylase , disaccharide , stereochemistry , enzyme , organic chemistry , purine nucleoside phosphorylase , purine , spray drying
A gene cluster involved in maltodextrin transport and metabolism was identified in the genome of Lactobacillus acidophilus NCFM, which encoded a maltodextrin‐binding protein, three maltodextrin ATP‐binding cassette transporters and five glycosidases, all under the control of a transcriptional regulator of the LacI‐GalR family. Enzymatic properties are described for recombinant maltose phosphorylase (MalP) of glycoside hydrolase family 65 (GH65), which is encoded by malP (GenBank: AAV43670 .1) of this gene cluster and produced in Escherichia coli . MalP catalyses phosphorolysis of maltose with inversion of the anomeric configuration releasing β‐glucose 1‐phosphate (β‐Glc 1‐P) and glucose. The broad specificity of the aglycone binding site was demonstrated by products formed in reverse phosphorolysis using various carbohydrate acceptor substrates and β‐Glc 1‐P as the donor. MalP showed strong preference for monosaccharide acceptors with equatorial 3‐OH and 4‐OH, such as glucose and mannose, and also reacted with 2‐deoxy glucosamine and 2‐deoxy N ‐acetyl glucosamine. By contrast, none of the tested di‐ and trisaccharides served as acceptors. Disaccharide yields obtained from 50 m m β‐Glc 1‐P and 50 m m glucose, glucosamine, N ‐acetyl glucosamine, mannose, xylose or l ‐fucose were 99, 80, 53, 93, 81 and 13%, respectively. Product structures were determined by NMR and ESI‐MS to be α‐Glc p ‐(1→4)‐Glc p (maltose), α‐Glc p ‐(1→4)‐GlcN p (maltosamine), α‐Glc p ‐(1→4)‐GlcNAc p ( N ‐acetyl maltosamine), α‐Glc p ‐(1→4)‐Man p , α‐Glc p ‐(1→4)‐Xyl p and α‐Glc p ‐(1→4)‐ l ‐Fuc p , the three latter being novel compounds. Modelling using L. brevis GH65 as the template and superimposition of acarbose from a complex with Thermoanaerobacterium thermosaccharolyticum GH15 glucoamylase suggested that loop 3 of MalP involved in substrate recognition blocked the binding of candidate acceptors larger than monosaccharides.