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Nutho B, Pengthaisong S, Tankrathok A, Lee VS, Ketudat Cairns JR, Rungrotmongkol T, Hannongbua S. Structural Basis of Specific Glucoimidazole and Mannoimidazole Binding by Os3BGlu7. Biomolecules 2020; 10:biom10060907. [PMID: 32549280 PMCID: PMC7356692 DOI: 10.3390/biom10060907] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 06/09/2020] [Accepted: 06/11/2020] [Indexed: 01/07/2023] Open
Abstract
β-Glucosidases and β-mannosidases hydrolyze substrates that differ only in the epimer of the nonreducing terminal sugar moiety, but most such enzymes show a strong preference for one activity or the other. Rice Os3BGlu7 and Os7BGlu26 β-glycosidases show a less strong preference, but Os3BGlu7 and Os7BGlu26 prefer glucosides and mannosides, respectively. Previous studies of crystal structures with glucoimidazole (GIm) and mannoimidazole (MIm) complexes and metadynamic simulations suggested that Os7BGlu26 hydrolyzes mannosides via the B2,5 transition state (TS) conformation preferred for mannosides and glucosides via their preferred 4H3/4E TS conformation. However, MIm is weakly bound by both enzymes. In the present study, we found that MIm was not bound in the active site of crystallized Os3BGlu7, but GIm was tightly bound in the -1 subsite in a 4H3/4E conformation via hydrogen bonds with the surrounding residues. One-microsecond molecular dynamics simulations showed that GIm was stably bound in the Os3BGlu7 active site and the glycone-binding site with little distortion. In contrast, MIm initialized in the B2,5 conformation rapidly relaxed to a E3/4H3 conformation and moved out into a position in the entrance of the active site, where it bound more stably despite making fewer interactions. The lack of MIm binding in the glycone site in protein crystals and simulations implies that the energy required to distort MIm to the B2,5 conformation for optimal active site residue interactions is sufficient to offset the energy of those interactions in Os3BGlu7. This balance between distortion and binding energy may also provide a rationale for glucosidase versus mannosidase specificity in plant β-glycosidases.
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Affiliation(s)
- Bodee Nutho
- Center of Excellence in Computational Chemistry (CECC), Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand;
| | - Salila Pengthaisong
- School of Chemistry, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand; (S.P.); (A.T.)
- Center for Biomolecular Structure, Function and Application, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand
| | - Anupong Tankrathok
- School of Chemistry, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand; (S.P.); (A.T.)
- Center for Biomolecular Structure, Function and Application, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand
| | - Vannajan Sanghiran Lee
- Department of Chemistry, Faculty of Science, University of Malaya, Kuala Lumpur 50603, Malaysia;
| | - James R. Ketudat Cairns
- School of Chemistry, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand; (S.P.); (A.T.)
- Center for Biomolecular Structure, Function and Application, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand
- Correspondence: (J.R.K.C.); (T.R.); (S.H.); Tel.: +66-4422-4304 (J.R.K.C.); +66-2218-5426 (T.R.); +66-2218-7602 (S.H.)
| | - Thanyada Rungrotmongkol
- Biocatalyst and Environmental Biotechnology Research Unit, Department of Biochemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand
- Program in Bioinformatics and Computational Biology, Graduate School, Chulalongkorn University, Bangkok 10330, Thailand
- Correspondence: (J.R.K.C.); (T.R.); (S.H.); Tel.: +66-4422-4304 (J.R.K.C.); +66-2218-5426 (T.R.); +66-2218-7602 (S.H.)
| | - Supot Hannongbua
- Center of Excellence in Computational Chemistry (CECC), Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand;
- Correspondence: (J.R.K.C.); (T.R.); (S.H.); Tel.: +66-4422-4304 (J.R.K.C.); +66-2218-5426 (T.R.); +66-2218-7602 (S.H.)
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Biocatalytic strategies in the production of galacto-oligosaccharides and its global status. Int J Biol Macromol 2018; 111:667-679. [DOI: 10.1016/j.ijbiomac.2018.01.062] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 12/20/2017] [Accepted: 01/10/2018] [Indexed: 01/03/2023]
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Investigation of the rescue mechanism catalyzed by a nucleophile mutant of rice BGlu1. J Mol Graph Model 2014; 54:100-6. [PMID: 25459761 DOI: 10.1016/j.jmgm.2014.10.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Revised: 09/30/2014] [Accepted: 10/08/2014] [Indexed: 11/22/2022]
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Gupta R, Govil T, Capalash N, Sharma P. Characterization of a glycoside hydrolase family 1 β-galactosidase from hot spring metagenome with transglycosylation activity. Appl Biochem Biotechnol 2012; 168:1681-93. [PMID: 23015191 DOI: 10.1007/s12010-012-9889-z] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Accepted: 08/30/2012] [Indexed: 11/29/2022]
Abstract
A novel, thermostable, alkalophilic β-D-galactosidase (Mbgl) was isolated from a metagenome of geothermal springs in northern Himalayan region of India. Mbgl was 447 amino acids in size and had conserved catalytic residues E170 and E358, indicating that it belonged to family 1 of glycosyl hydrolases showing maximum homology (89 %) with uncharacterized β-galactosidase of Eubacterium, Meiothermus ruber DSM1279. Temperature and pH optima of Mbgl were 65 °C and 8.0 respectively, and it retained 80 % activity even at pH 10.0. Mbgl was active as a homotetramer, recognized β-(1,4)-D-galactoside as the preferred glycosidic bond, and preferentially hydrolyzed pNPgal with K(m) 3.33 mM and k(cat) 2,000 s(-1). It displayed high transglycosylation activity with wide acceptor specificity including hexoses and pentoses leading to the formation of prebiotic galacto-oligosaccharides whereas its lactose hydrolysis potential was low.
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Affiliation(s)
- Richa Gupta
- Department of Biotechnology, Panjab University, Chandigarh 160014, India
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QM/MM studies on the glycosylation mechanism of rice BGlu1 β-glucosidase. J Mol Graph Model 2011; 30:148-52. [DOI: 10.1016/j.jmgm.2011.06.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2011] [Revised: 06/24/2011] [Accepted: 06/30/2011] [Indexed: 11/24/2022]
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The structural basis of oligosaccharide binding by rice BGlu1 beta-glucosidase. J Struct Biol 2010; 173:169-79. [PMID: 20884352 DOI: 10.1016/j.jsb.2010.09.021] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2010] [Revised: 08/27/2010] [Accepted: 09/22/2010] [Indexed: 11/23/2022]
Abstract
Rice BGlu1 β-glucosidase is an oligosaccharide exoglucosidase that binds to six β-(1→4)-linked glucosyl residues in its active site cleft. Here, we demonstrate that a BGlu1 E176Q active site mutant can be effectively rescued by small nucleophiles, such as acetate, azide and ascorbate, for hydrolysis of aryl glycosides in a pH-independent manner above pH5, consistent with the role of E176 as the catalytic acid-base. Cellotriose, cellotetraose, cellopentaose, cellohexaose and laminaribiose are not hydrolyzed by the mutant and instead exhibit competitive inhibition. The structures of the BGlu1 E176Q, its complexes with cellotetraose, cellopentaose and laminaribiose, and its covalent intermediate with 2-deoxy-2-fluoroglucoside were determined at 1.65, 1.95, 1.80, 2.80, and 1.90Å resolution, respectively. The Q176Nε was found to hydrogen bond to the glycosidic oxygen of the scissile bond, thereby explaining its high activity. The enzyme interacts with cellooligosaccharides through direct hydrogen bonds to the nonreducing terminal glucosyl residue. However, interaction with the other glucosyl residues is predominantly mediated through water molecules, with the exception of a direct hydrogen bond from N245 to glucosyl residue 3, consistent with the apparent high binding energy at this residue. Hydrophobic interactions with the aromatic sidechain of W358 appear to orient glucosyl residues 2 and 3, while Y341 orients glucosyl residues 4 and 5. In contrast, laminaribiose has its second glucosyl residue positioned to allow direct hydrogen bonding between its O2 and Q176 Oε and O1 and N245. These are the first GH1 glycoside hydrolase family structures to show oligosaccharide binding in the hydrolytic configuration.
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Seshadri S, Akiyama T, Opassiri R, Kuaprasert B, Cairns JK. Structural and enzymatic characterization of Os3BGlu6, a rice beta-glucosidase hydrolyzing hydrophobic glycosides and (1->3)- and (1->2)-linked disaccharides. PLANT PHYSIOLOGY 2009; 151:47-58. [PMID: 19587102 PMCID: PMC2735989 DOI: 10.1104/pp.109.139436] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2009] [Accepted: 07/02/2009] [Indexed: 05/18/2023]
Abstract
Glycoside hydrolase family 1 (GH1) beta-glucosidases play roles in many processes in plants, such as chemical defense, alkaloid metabolism, hydrolysis of cell wall-derived oligosaccharides, phytohormone regulation, and lignification. However, the functions of most of the 34 GH1 gene products in rice (Oryza sativa) are unknown. Os3BGlu6, a rice beta-glucosidase representing a previously uncharacterized phylogenetic cluster of GH1, was produced in recombinant Escherichia coli. Os3BGlu6 hydrolyzed p-nitrophenyl (pNP)-beta-d-fucoside (k(cat)/K(m) = 67 mm(-1) s(-1)), pNP-beta-d-glucoside (k(cat)/K(m) = 6.2 mm(-1) s(-1)), and pNP-beta-d-galactoside (k(cat)/K(m) = 1.6 mm(-1)s(-1)) efficiently but had little activity toward other pNP glycosides. It also had high activity toward n-octyl-beta-d-glucoside and beta-(1-->3)- and beta-(1-->2)-linked disaccharides and was able to hydrolyze apigenin beta-glucoside and several other natural glycosides. Crystal structures of Os3BGlu6 and its complexes with a covalent intermediate, 2-deoxy-2-fluoroglucoside, and a nonhydrolyzable substrate analog, n-octyl-beta-d-thioglucopyranoside, were solved at 1.83, 1.81, and 1.80 A resolution, respectively. The position of the covalently trapped 2-F-glucosyl residue in the enzyme was similar to that in a 2-F-glucosyl intermediate complex of Os3BGlu7 (rice BGlu1). The side chain of methionine-251 in the mouth of the active site appeared to block the binding of extended beta-(1-->4)-linked oligosaccharides and interact with the hydrophobic aglycone of n-octyl-beta-d-thioglucopyranoside. This correlates with the preference of Os3BGlu6 for short oligosaccharides and hydrophobic glycosides.
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Affiliation(s)
- Supriya Seshadri
- School of Biochemistry, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand
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Chuenchor W, Pengthaisong S, Robinson RC, Yuvaniyama J, Oonanant W, Bevan DR, Esen A, Chen CJ, Opassiri R, Svasti J, Cairns JRK. Structural Insights into Rice BGlu1 β-Glucosidase Oligosaccharide Hydrolysis and Transglycosylation. J Mol Biol 2008; 377:1200-15. [DOI: 10.1016/j.jmb.2008.01.076] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2007] [Revised: 01/07/2008] [Accepted: 01/24/2008] [Indexed: 11/16/2022]
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Tribolo S, Berrin JG, Kroon PA, Czjzek M, Juge N. The Crystal Structure of Human Cytosolic β-Glucosidase Unravels the Substrate Aglycone Specificity of a Family 1 Glycoside Hydrolase. J Mol Biol 2007; 370:964-75. [PMID: 17555766 DOI: 10.1016/j.jmb.2007.05.034] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2007] [Revised: 04/27/2007] [Accepted: 05/12/2007] [Indexed: 11/22/2022]
Abstract
Human cytosolic beta-glucosidase (hCBG) is a xenobiotic-metabolizing enzyme that hydrolyses certain flavonoid glucosides, with specificity depending on the aglycone moiety, the type of sugar and the linkage between them. In this study, the substrate preference of this enzyme was investigated by mutational analysis, X-ray crystallography and homology modelling. The crystal structure of hCBG was solved by the molecular replacement method and refined at 2.7 A resolution. The main-chain fold of the enzyme belongs to the (beta/alpha)(8) barrel structure, which is common to family 1 glycoside hydrolases. The active site is located at the bottom of a pocket (about 16 A deep) formed by large surface loops, surrounding the C termini of the barrel of beta-strands. As for all the clan of GH-A enzymes, the two catalytic glutamate residues are located on strand 4 (the acid/base Glu165) and on strand 7 (the nucleophile Glu373). Although many features of hCBG were shown to be very similar to previously described enzymes from this family, crucial differences were observed in the surface loops surrounding the aglycone binding site, and these are likely to strongly influence the substrate specificity. The positioning of a substrate molecule (quercetin-4'-glucoside) by homology modelling revealed that hydrophobic interactions dominate the binding of the aglycone moiety. In particular, Val168, Trp345, Phe225, Phe179, Phe334 and Phe433 were identified as likely to be important in determining substrate specificity in hCBG, and site-directed mutagenesis supported a key role for some of these residues.
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Affiliation(s)
- Sandra Tribolo
- Institute of Food Research, Norwich Research Park, Colney, Norwich NR4 7UA, UK
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