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Acremonium strictum

The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform

Shwu Huey Liaw – 1st expert on this subject based on the ideXlab platform

  • functional roles of the 6 s cysteinyl 8alpha n1 histidyl fad in glucooligosaccharide oxidase from Acremonium strictum
    Journal of Biological Chemistry, 2008
    Co-Authors: Chun Hsiang Huang, Ying Chieh Tsai, Andreas Winkler, Chialin Chen, Peter Macheroux, Shwu Huey Liaw

    Abstract:

    Abstract The crystal structure of glucooligosaccharide oxidase from Acremonium strictum was demonstrated to contain a bicovalent flavinylation, with the 6- and 8α-positions of the flavin isoalloxazine ring cross-linked to Cys130 and His70, respectively. The H70A and C130A single mutants still retain the covalent FAD, indicating that flavinylation at these two residues is independent. Both mutants exhibit a decreased midpoint potential of ∼+69 and +61 mV, respectively, compared with +126 mV for the wild type, and possess lower activities with kcat values reduced to ∼2 and 5%, and the flavin reduction rate reduced to 0.6 and 14%. This indicates that both covalent linkages increase the flavin redox potential and alter the redox properties to promote catalytic efficiency. In addition, the isolated H70A/C130A double mutant does not contain FAD, and addition of exogenous FAD was not able to restore any detectable activity. This demonstrates that the covalent attachment is essential for the binding of the oxidized cofactor. Furthermore, the crystal structure of the C130A mutant displays conformational changes in several cofactor and substrate-interacting residues and hence provides direct evidence for novel functions of flavinylation in assistance of cofactor and substrate binding. Finally, the wild-type enzyme is more heat and guanidine HCl-resistant than the mutants. Therefore, the bicovalent flavin linkage not only tunes the redox potential and contributes to cofactor and substrate binding but also increases structural stability.

  • structural characterization of glucooligosaccharide oxidase from Acremonium strictum
    Applied and Environmental Microbiology, 2005
    Co-Authors: Shwu Huey Liaw, Ying Chieh Tsai

    Abstract:

    Glucooligosaccharide oxidase from Acremonium strictum was screened for potential applications in oligosaccharide acid production and carbohydrate detection. This protein is a unique covalent flavoenzyme which catalyzes the oxidation of a variety of carbohydrates with high selectivity for cello- and maltooligosaccharides. Kinetic measurements suggested that this enzyme possesses an open carbohydrate-binding groove, which is mainly composed of two glucosyl-binding subsites. The encoding gene was subsequently cloned, and one intron was detected in the genomic DNA. Large amounts of active enzymes were expressed in Pichia pastoris, with a yield of 300 mg per liter medium. The protein was predicted to share structural homology with plant cytokinin dehydrogenase and related flavoproteins that share a conserved flavin adenine dinucleotide (FAD)-binding domain. The closest sequence matches are those of plant berberine bridge enzyme-like proteins, particularly the characteristic flavinylation site. Unexpectedly, mutation of the putative FAD-attaching residue, H70, to alanine, serine, cysteine, and tyrosine did not abolish the covalent FAD linkage and had little effect on the Km. Instead, the variants displayed kcat values that were 50- to 600-fold lower, indicating that H70 is crucial for efficient redox catalysis, perhaps through modulation of the oxidative power of the flavin.

  • crystal structure of glucooligosaccharide oxidase from Acremonium strictum a novel flavinylation of 6 s cysteinyl 8alpha n1 histidyl fad
    Journal of Biological Chemistry, 2005
    Co-Authors: Chun Hsiang Huang, Chun Jung Chen, Andrea Vasella, Ying Chieh Tsai, Shwu Huey Liaw

    Abstract:

    Abstract Glucooligosaccharide oxidase from Acremonium strictum has been screened for potential applications in oligosaccharide acid production and alternative carbohydrate detection, because it catalyzes the oxidation of glucose, maltose, lactose, cellobiose and cello- and maltooligosaccharides. We report the crystal structures of the enzyme and of its complex with an inhibitor, 5-amino-5-deoxy- cellobiono-1,5-lactam at 1.55- and 1.98-A resolution, respectively. Unexpectedly, the protein structure demonstrates the first known double attachment flavinylation, 6-S-cysteinyl, 8α-N1-histidyl FAD. The FAD cofactor is cross-linked to the enzyme via the C6 atom and the 8α-methyl group of the isoalloxazine ring with Cys130 and His70, respectively. This sugar oxidase possesses an open carbohydrate-binding groove, allowing the accommodation of higher oligosaccharides. The complex structure suggests that this enzyme may prefer a β-d-glucosyl residue at the reducing end with the conserved Tyr429 acting as a general base to abstract the OH1 proton in concert with the H1 hydride transfer to the flavin N5. Finally, a detailed comparison illustrates the structural conservation as well as the divergence between this protein and its related flavoenzymes.

Thomas J Simpson – 2nd expert on this subject based on the ideXlab platform

  • Structure elucidation and synthesis of (4S,5S,6Z,8E)-5-hydroxydeca-6,8-dien-4-olide [(S,S)-sapinofuranone B]—a novel γ-lactone metabolite of Acremonium strictum
    Journal of The Chemical Society-perkin Transactions 1, 2020
    Co-Authors: Sarah Clough, Thomas J Simpson, Mairi E. Raggatt, Christine L. Willis, Andrew Whiting, Stephen K. Wrigley

    Abstract:

    The structure of (4S,5S,6Z,8E)-5-hydroxydeca-6,8-dien-4-olide, a novel metabolite of Acremonium strictum, has been established by spectroscopic studies and chemical correlation with the known L-factor. The structure has been confirmed by a total synthesis in which the asymmetric centres at C-4 and C-5 were elaborated from dimethyl L-tartrate and the 6,8-diene moiety was introduced via Stille coupling of (E)-prop-1-enyltributyltin with a (Z)-vinylic iodide. The absolute configurations of sapinofuranones A and B, recently isolated metabolites of Sphaeropsis sapinae, are shown to be the corresponding (4R,5S) and (4R,5R) diastereomers of the A. strictum metabolite.

  • characterisation of 3 methylorcinaldehyde synthase mos in Acremonium strictum first observation of a reductive release mechanism during polyketide biosynthesis
    Chemical Communications, 2007
    Co-Authors: Andy M Bailey, Kate Harley, Colin M Lazarus, Thomas J Simpson, Elizabeth Skellam

    Abstract:

    Isolation and sequencing of a PKS gene isolated from xenovulene-producing cultures of Acremonium strictum indicated the presence of NT-, KS-, AT-, PT-, C-MeT- and R-domains; heterologous expression in Aspergillus oryzae resulted in the production of 3-methylorcinaldehyde, demonstrating the role of the terminal reductase domain in product release.

  • structure elucidation and synthesis of 4s 5s 6z 8e 5 hydroxydeca 6 8 dien 4 olide s s sapinofuranone b a novel γ lactone metabolite of Acremonium strictum
    Journal of The Chemical Society-perkin Transactions 1, 2000
    Co-Authors: Sarah Clough, Thomas J Simpson, Mairi E. Raggatt, Christine L. Willis, Andrew Whiting, Stephen K. Wrigley

    Abstract:

    The structure of (4S,5S,6Z,8E)-5-hydroxydeca-6,8-dien-4-olide, a novel metabolite of Acremonium strictum, has been established by spectroscopic studies and chemical correlation with the known L-factor. The structure has been confirmed by a total synthesis in which the asymmetric centres at C-4 and C-5 were elaborated from dimethyl L-tartrate and the 6,8-diene moiety was introduced via Stille coupling of (E)-prop-1-enyltributyltin with a (Z)-vinylic iodide. The absolute configurations of sapinofuranones A and B, recently isolated metabolites of Sphaeropsis sapinae, are shown to be the corresponding (4R,5S) and (4R,5R) diastereomers of the A. strictum metabolite.

Chun Hsiang Huang – 3rd expert on this subject based on the ideXlab platform

  • functional roles of the 6 s cysteinyl 8alpha n1 histidyl fad in glucooligosaccharide oxidase from Acremonium strictum
    Journal of Biological Chemistry, 2008
    Co-Authors: Chun Hsiang Huang, Ying Chieh Tsai, Andreas Winkler, Chialin Chen, Peter Macheroux, Shwu Huey Liaw

    Abstract:

    Abstract The crystal structure of glucooligosaccharide oxidase from Acremonium strictum was demonstrated to contain a bicovalent flavinylation, with the 6- and 8α-positions of the flavin isoalloxazine ring cross-linked to Cys130 and His70, respectively. The H70A and C130A single mutants still retain the covalent FAD, indicating that flavinylation at these two residues is independent. Both mutants exhibit a decreased midpoint potential of ∼+69 and +61 mV, respectively, compared with +126 mV for the wild type, and possess lower activities with kcat values reduced to ∼2 and 5%, and the flavin reduction rate reduced to 0.6 and 14%. This indicates that both covalent linkages increase the flavin redox potential and alter the redox properties to promote catalytic efficiency. In addition, the isolated H70A/C130A double mutant does not contain FAD, and addition of exogenous FAD was not able to restore any detectable activity. This demonstrates that the covalent attachment is essential for the binding of the oxidized cofactor. Furthermore, the crystal structure of the C130A mutant displays conformational changes in several cofactor and substrate-interacting residues and hence provides direct evidence for novel functions of flavinylation in assistance of cofactor and substrate binding. Finally, the wild-type enzyme is more heat and guanidine HCl-resistant than the mutants. Therefore, the bicovalent flavin linkage not only tunes the redox potential and contributes to cofactor and substrate binding but also increases structural stability.

  • crystal structure of glucooligosaccharide oxidase from Acremonium strictum a novel flavinylation of 6 s cysteinyl 8alpha n1 histidyl fad
    Journal of Biological Chemistry, 2005
    Co-Authors: Chun Hsiang Huang, Chun Jung Chen, Andrea Vasella, Ying Chieh Tsai, Shwu Huey Liaw

    Abstract:

    Abstract Glucooligosaccharide oxidase from Acremonium strictum has been screened for potential applications in oligosaccharide acid production and alternative carbohydrate detection, because it catalyzes the oxidation of glucose, maltose, lactose, cellobiose and cello- and maltooligosaccharides. We report the crystal structures of the enzyme and of its complex with an inhibitor, 5-amino-5-deoxy- cellobiono-1,5-lactam at 1.55- and 1.98-A resolution, respectively. Unexpectedly, the protein structure demonstrates the first known double attachment flavinylation, 6-S-cysteinyl, 8α-N1-histidyl FAD. The FAD cofactor is cross-linked to the enzyme via the C6 atom and the 8α-methyl group of the isoalloxazine ring with Cys130 and His70, respectively. This sugar oxidase possesses an open carbohydrate-binding groove, allowing the accommodation of higher oligosaccharides. The complex structure suggests that this enzyme may prefer a β-d-glucosyl residue at the reducing end with the conserved Tyr429 acting as a general base to abstract the OH1 proton in concert with the H1 hydride transfer to the flavin N5. Finally, a detailed comparison illustrates the structural conservation as well as the divergence between this protein and its related flavoenzymes.

  • Crystal structure of glucooligosaccharide oxidase from Acremonium strictum: A novel flavinylation of 6-S-cysteinyl, 8α-N1-histidyl FAD
    Journal of Biological Chemistry, 2005
    Co-Authors: Chun Hsiang Huang, Wen Lin Lai, Meng Hwan Lee, Chun Jung Chen, Andrea Vasella, Ying Chieh Tsai, Shwu Huey Liaw

    Abstract:

    Glucooligosaccharide oxidase from Acremonium strictum has been screened for potential applications in oligosaccharide acid production and alternative carbohydrate detection, because it catalyzes the oxidation of glucose, maltose, lactose, cellobiose and cello- and maltooligosaccharides. We report the crystal structures of the enzyme and of its complex with an inhibitor, 5-amino-5-deoxy- cellobiono-1,5-lactam at 1.55- and 1.98-A resolution, respectively. Unexpectedly, the protein structure demonstrates the first known double attachment flavinylation, 6-S-cysteinyl, 8alpha-N1-histidyl FAD. The FAD cofactor is cross-linked to the enzyme via the C(6) atom and the 8alpha-methyl group of the isoalloxazine ring with Cys(130) and His(70), respectively. This sugar oxidase possesses an open carbohydrate-binding groove, allowing the accommodation of higher oligosaccharides. The complex structure suggests that this enzyme may prefer a beta-d-glucosyl residue at the reducing end with the conserved Tyr(429) acting as a general base to abstract the OH(1) proton in concert with the H(1) hydride transfer to the flavin N(5). Finally, a detailed comparison illustrates the structural conservation as well as the divergence between this protein and its related flavoenzymes.