liver, oyster, or mycobacterial glycogens are the best acceptors, amylopectin has good activity, but amylose is a poor acceptor. GMPMT also appears to be able to catalyze arsenolysis of glycogen with release of malto-oligosaccharides or at least maltotriose
liver, oyster, or mycobacterial glycogens are the best acceptors, amylopectin has good activity, but amylose is a poor acceptor. GMPMT also appears to be able to catalyze arsenolysis of glycogen with release of malto-oligosaccharides or at least maltotriose
acceptor and secondary binding sites are identified. The sugar residues in the acceptor subsites +1 to +5 are oriented such that they disfavor the binding of malto-oligosaccharides that bear branches at their 6-positions, consistent with the known acceptor chain specificity of GlgE. A secondary binding site remote from the catalytic center is identified. This site is capable of binding a branched alpha-glucan and is most likely involved in guiding acceptors toward the donor site because its disruption kinetically compromises the ability of GlgE to extend polymeric substrates
acceptor and secondary binding sites are identified. The sugar residues in the acceptor subsites +1 to +5 are oriented such that they disfavor the binding of malto-oligosaccharides that bear branches at their 6-positions, consistent with the known acceptor chain specificity of GlgE. A secondary binding site remote from the catalytic center is identified. This site is capable of binding a branched alpha-glucan and is most likely involved in guiding acceptors toward the donor site because its disruption kinetically compromises the ability of GlgE to extend polymeric substrates
GMPMT requires a high-molecular weight alpha-1,4-glucan as the acceptor. The enzyme can also transfer maltosyl units to maltosaccharides, e.g. maltotetraose to maltohexaose, overview
GMPMT requires a high-molecular weight alpha-1,4-glucan as the acceptor. The enzyme can also transfer maltosyl units to maltosaccharides, e.g. maltotetraose to maltohexaose, overview
GMPMT requires a high-molecular weight alpha-1,4-glucan as the acceptor. The enzyme can also transfer maltosyl units to maltosaccharides, e.g. maltotetraose to maltohexaose, overview
the enzyme catalyzes the transfer of maltosyl units from alpha-1,4-linked glucans or malto-oligosaccharides to other alpha-1,4-linked glucans, malto-oligosaccharides or glucose. Analysis of maltose binding in the active site reveals that the transfer of dextrinyl residues longer than a maltosyl unit is prevented by termination of the active-site cleft after the -2 subsite by the side-chain of Lys151 and the stretch of residues 314-317, providing an explanation for the strict transfer specificity of MTase
after preincubation for 5 min with 1 mM substrate analogue 2-deoxy-2-fluoro-alpha-maltosyl fluoride, 70% of the normal activity with alpha-maltose 1-phosphate is lost
Mycobacterium tuberculosis maltosyltransferase GlgE, a genetically validated antituberculosis target, is negatively regulated by Ser/Thr phosphorylation.
a constructed DELTAglgE null mutant strain was viable but shows a delayed developmental phenotype when grown on maltose, giving less cell mass and delayed sporulation. Pre-spore cells and spores of the mutant are frequently double the length of those of the wild-type, implying impaired cross-wall formation, and spores show reduced tolerance to stress. The mutant accumulates alpha-maltose 1-phosphate and maltose but no alpha-glucan
a constructed DELTAglgE null mutant strain was viable but shows a delayed developmental phenotype when grown on maltose, giving less cell mass and delayed sporulation. Pre-spore cells and spores of the mutant are frequently double the length of those of the wild-type, implying impaired cross-wall formation, and spores show reduced tolerance to stress. The mutant accumulates alpha-maltose 1-phosphate and maltose but no alpha-glucan
the enzyme catalyzes the last step in the conversion of trehalose to glycogen transfering maltose from maltose 1-phosphate to glycogen. Trehalose synthase, maltokinase, and GMPMT represent an additional pathway of glycogen synthesis using trehalose as the source of glucose
the following assembly mechanism is proposed. Polymer synthesis starts with GlgE and its donor substrate, alpha-maltose 1-phosphate, yielding a linear oligomer with a degree of polymerization (of about 16) sufficient for GlgB to introduce a branch. Branching involves strictly intrachain transfer to generate a C chain (the only constituent chain to retain its reducing end), which now bears an A chain (a nonreducing end terminal branch that does not itself bear a branch). GlgE preferentially extends A chains allowing GlgB to act iteratively to generate new A chains emanating from B chains (nonterminal branches that themselves bear a branch). Although extension and branching occur primarily with A chains, the other chain types are sometimes extended and branched such that some B chains (and possibly C chains) bear more than one branch
the following assembly mechanism is proposed. Polymer synthesis starts with GlgE and its donor substrate, alpha-maltose 1-phosphate, yielding a linear oligomer with a degree of polymerization (of about 16) sufficient for GlgB to introduce a branch. Branching involves strictly intrachain transfer to generate a C chain (the only constituent chain to retain its reducing end), which now bears an A chain (a nonreducing end terminal branch that does not itself bear a branch). GlgE preferentially extends A chains allowing GlgB to act iteratively to generate new A chains emanating from B chains (nonterminal branches that themselves bear a branch). Although extension and branching occur primarily with A chains, the other chain types are sometimes extended and branched such that some B chains (and possibly C chains) bear more than one branch
the enzyme catalyzes the last step in the conversion of trehalose to glycogen transfering maltose from maltose 1-phosphate to glycogen. Trehalose synthase, maltokinase, and GMPMT represent an additional pathway of glycogen synthesis using trehalose as the source of glucose
the following assembly mechanism is proposed. Polymer synthesis starts with GlgE and its donor substrate, alpha-maltose 1-phosphate, yielding a linear oligomer with a degree of polymerization (of about 16) sufficient for GlgB to introduce a branch. Branching involves strictly intrachain transfer to generate a C chain (the only constituent chain to retain its reducing end), which now bears an A chain (a nonreducing end terminal branch that does not itself bear a branch). GlgE preferentially extends A chains allowing GlgB to act iteratively to generate new A chains emanating from B chains (nonterminal branches that themselves bear a branch). Although extension and branching occur primarily with A chains, the other chain types are sometimes extended and branched such that some B chains (and possibly C chains) bear more than one branch
the following assembly mechanism is proposed. Polymer synthesis starts with GlgE and its donor substrate, alpha-maltose 1-phosphate, yielding a linear oligomer with a degree of polymerization (of about 16) sufficient for GlgB to introduce a branch. Branching involves strictly intrachain transfer to generate a C chain (the only constituent chain to retain its reducing end), which now bears an A chain (a nonreducing end terminal branch that does not itself bear a branch). GlgE preferentially extends A chains allowing GlgB to act iteratively to generate new A chains emanating from B chains (nonterminal branches that themselves bear a branch). Although extension and branching occur primarily with A chains, the other chain types are sometimes extended and branched such that some B chains (and possibly C chains) bear more than one branch
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CRYSTALLIZATION (Commentary)
ORGANISM
UNIPROT
LITERATURE
alpha-maltose 1-phosphate bound to a D394A mutant and beta-2-deoxy-2-fluoromaltosyl-enzyme intermediate with a E423A mutant is crystallized with 15% (w/v) polyethylene glycol 3350, 0.2 M sodium citrate, and 15% (w/v) ethylene glycol
crystal structures of the enzyme and its complex with maltose are determined at 2.4 A and 2.1 A resolution. Crystals belong to space group P4(1)22 with unit-cell dimensions a = b = 148.7 A, c = 106.7 A
a coumarin-based Cu(II)-mDPA sensor (Cu-1b) is developed using internal charge transfer as the sensing mechanism for the selective detection of phosphate ions in HEPES buffer with an association constant of 140000/M. The Cu(II)-di(methylpyridylmethyl)amine-coumarin sensor acts as a robust and sensitive sensor to probe the enzyme-catalyzed reaction. This fluorescence turn-on assay may facilitate the screening of GlgE inhibitors for the discovery of new anti-tuberculosis drugs
a coumarin-based Cu(II)-mDPA sensor (Cu-1b) is developed using internal charge transfer as the sensing mechanism for the selective detection of phosphate ions in HEPES buffer with an association constant of 140000/M. The Cu(II)-di(methylpyridylmethyl)amine-coumarin sensor acts as a robust and sensitive sensor to probe the enzyme-catalyzed reaction. This fluorescence turn-on assay may facilitate the screening of GlgE inhibitors for the discovery of new anti-tuberculosis drugs
Syson, K.; Stevenson, C.E.; Miah, F.; Barclay, J.E.; Tang, M.; Gorelik, A.; Rashid, A.M.; Lawson, D.M.; Bornemann, S.
Ligand-bound structures and site-directed mutagenesis identify the acceptor and secondary binding sites of Streptomyces coelicolor maltosyltransferase GlgE