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Wali S, Atia-Tul-Wahab, Ullah S, Khan MA, Hussain S, Shaikh M, Atta-Ur-Rahman, Choudhary MI. Synthesis of new clioquinol derivatives as potent α-glucosidase inhibitors; molecular docking, kinetic and structure-activity relationship studies. Bioorg Chem 2021; 119:105506. [PMID: 34896920 DOI: 10.1016/j.bioorg.2021.105506] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 11/11/2021] [Accepted: 11/17/2021] [Indexed: 12/14/2022]
Abstract
Diabetes mellitus is a chronic metabolic disorder with increasing prevalence and long-term complications. The aim of this study was to identify α-glucosidase inhibitory compounds with potential anti-hyperglycemic activity. For this purpose, a series of new clioquinol derivatives 2a-11a was synthesized, and characterized by various spectroscopic techniques. The enzyme inhibitory activities of the resulting derivatives were assessed using an in-vitro mechanism-based assay. All the tested compounds 2a-11a of the series showed a significant α-glucosidase inhibition with IC50 values 43.86-325.81 µM, as compared to the standard drug acarbose 1C50: 875.75 ± 2.08 µM. Among them, compounds 4a, 5a, 10a, and 11a showed IC50 values of 105.51 ± 2.41, 119.24 ± 2.37, 99.15 ± 2.06, and 43.86 ± 2.71 µM, respectively. Kinetic study of the active analogues showed competitive, non-competitive, and mixed-type inhibitions. Furthermore, the molecular docking study was performed to elucidate the binding interactions of most active analogues with the various sites of α-glucosidase enzyme. The results indicate that these compounds have the potential to be further studied as new anti-diabetic agents.
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Affiliation(s)
- Shoukat Wali
- H. E. J. Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi, Karachi 75270, Pakistan
| | - Atia-Tul-Wahab
- Dr. Panjwani Center for Molecular Medicine and Drug Research, International Center for Chemical and Biological Sciences, University of Karachi, Karachi 75270, Pakistan.
| | - Saeed Ullah
- H. E. J. Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi, Karachi 75270, Pakistan
| | - Maria Aqeel Khan
- Third World Center for Science and Technology International Center for Chemical and Biological Sciences, University of Karachi, Karachi 75270, Pakistan
| | - Shahid Hussain
- Toronto General Hospital Research Institute (TGHRI), Toronto M5G 2C4, Canada
| | - Muniza Shaikh
- Dr. Panjwani Center for Molecular Medicine and Drug Research, International Center for Chemical and Biological Sciences, University of Karachi, Karachi 75270, Pakistan
| | - Atta-Ur-Rahman
- H. E. J. Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi, Karachi 75270, Pakistan; Dr. Panjwani Center for Molecular Medicine and Drug Research, International Center for Chemical and Biological Sciences, University of Karachi, Karachi 75270, Pakistan
| | - M Iqbal Choudhary
- H. E. J. Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi, Karachi 75270, Pakistan; Dr. Panjwani Center for Molecular Medicine and Drug Research, International Center for Chemical and Biological Sciences, University of Karachi, Karachi 75270, Pakistan; Department of Biochemistry, Faculty of Science King Abdulaziz University, Jeddah 22254, Saudi Arabia.
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2
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Malik NP, Naz M, Ashiq U, Jamal RA, Gul S, Saleem F, Khan KM, Yousuf S. Oxamide Derivatives as Potent
α
‐Glucosidase Inhibitors: Design, Synthesis,
In Vitro
Inhibitory Screening and
In Silico
Docking Studies. ChemistrySelect 2021. [DOI: 10.1002/slct.202101709] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
| | - Maira Naz
- Department of Chemistry University of Karachi Karachi 75270 Pakistan
| | - Uzma Ashiq
- Department of Chemistry University of Karachi Karachi 75270 Pakistan
| | - Rifat A. Jamal
- Department of Chemistry University of Karachi Karachi 75270 Pakistan
| | - Sana Gul
- Department of Chemistry Federal Urdu University of Art Science and Technology Karachi Pakistan
| | - Faiza Saleem
- H. E. J. Research Institute of Chemistry International Center for Chemical and Biological Sciences University of Karachi Karachi 75270 Pakistan
| | - Khalid M. Khan
- H. E. J. Research Institute of Chemistry International Center for Chemical and Biological Sciences University of Karachi Karachi 75270 Pakistan
- Department of Clinical Pharmacy Institute for Research and Medical Consultations (IRMC) Imam Abdulrahman Bin Faisal University P.O. Box 1982 Dammam 31441 Saudi Arabia
| | - Sammer Yousuf
- H. E. J. Research Institute of Chemistry International Center for Chemical and Biological Sciences University of Karachi Karachi 75270 Pakistan
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3
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Shaheen A, Ashiq U, Jamal RA, Khan KM, Gul S, Yousuf S, Ali ST. Design and Synthesis of Fluoroquinolone Derivatives as Potent α‐Glucosidase Inhibitors: In Vitro Inhibitory Screening with In Silico Docking Studies. ChemistrySelect 2021. [DOI: 10.1002/slct.202003956] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Aasia Shaheen
- Department of Chemistry University of Karachi Karachi 75270 Pakistan
| | - Uzma Ashiq
- Department of Chemistry University of Karachi Karachi 75270 Pakistan
| | - Rifat Ara Jamal
- Department of Chemistry University of Karachi Karachi 75270 Pakistan
| | - Khalid Mohammed Khan
- H. E. J. Research Institute of Chemistry International Center for Chemical and Biological Sciences University of Karachi Karachi 75270 Pakistan
- Department of Clinical Pharmacy Institute for Research and Medical Consultations (IRMC) Imam Abdulrahman Bin Faisal University, P.O. Box 1982 Dammam 31441 Saudi Arabia
| | - Sana Gul
- Department of Chemistry Federal Urdu University of Art, Science and Technology Karachi Pakistan
| | - Sammer Yousuf
- H. E. J. Research Institute of Chemistry International Center for Chemical and Biological Sciences University of Karachi Karachi 75270 Pakistan
| | - Syed Tahir Ali
- Department of Chemistry Federal Urdu University of Art, Science and Technology Karachi Pakistan
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4
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Crystal structure and substrate-binding mode of GH63 mannosylglycerate hydrolase from Thermus thermophilus HB8. J Struct Biol 2015; 190:21-30. [DOI: 10.1016/j.jsb.2015.02.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Revised: 02/16/2015] [Accepted: 02/17/2015] [Indexed: 11/20/2022]
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5
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Shibuya A, Margulis N, Christiano R, Walther TC, Barlowe C. The Erv41-Erv46 complex serves as a retrograde receptor to retrieve escaped ER proteins. ACTA ACUST UNITED AC 2015; 208:197-209. [PMID: 25583996 PMCID: PMC4298680 DOI: 10.1083/jcb.201408024] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Signal-dependent sorting of proteins in the early secretory pathway is required for dynamic retention of endoplasmic reticulum (ER) and Golgi components. In this study, we identify the Erv41-Erv46 complex as a new retrograde receptor for retrieval of non-HDEL-bearing ER resident proteins. In cells lacking Erv41-Erv46 function, the ER enzyme glucosidase I (Gls1) was mislocalized and degraded in the vacuole. Biochemical experiments demonstrated that the luminal domain of Gls1 bound to the Erv41-Erv46 complex in a pH-dependent manner. Moreover, in vivo disturbance of the pH gradient across membranes by bafilomycin A1 treatment caused Gls1 mislocalization. Whole cell proteomic analyses of deletion strains using stable isotope labeling by amino acids in culture identified other ER resident proteins that depended on the Erv41-Erv46 complex for efficient localization. Our results support a model in which pH-dependent receptor binding of specific cargo by the Erv41-Erv46 complex in Golgi compartments identifies escaped ER resident proteins for retrieval to the ER in coat protein complex I-formed transport carriers.
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Affiliation(s)
- Aya Shibuya
- Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, NH 03755
| | - Neil Margulis
- Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, NH 03755
| | - Romain Christiano
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06520
| | - Tobias C Walther
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06520
| | - Charles Barlowe
- Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, NH 03755
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6
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Cruz IN, Barry CS, Kramer HB, Chuang CC, Lloyd S, van der Spoel AC, Platt FM, Yang M, Davis BG. Glycomimetic affinity-enrichment proteomics identifies partners for a clinically-utilized iminosugar. Chem Sci 2013; 4:3442-3446. [PMID: 31031905 PMCID: PMC6485602 DOI: 10.1039/c3sc50826a] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Widescale evaluation of interacting partners for carbohydrates is an underexploited area. Probing of the 'glyco-interactome' has particular relevance given the lack of direct genetic control of glycoconjugate biosynthesis. Here we design, create and utilize a natural product-derived glycomimetic iminosugar probe in a Glycomimetic Affinity-enrichment Proteomics (glyco-AeP) strategy to elucidate key interactions directly from mammalian tissue. The binding partners discovered here and the associated genomic analysis implicate a subset of chaperone and junctional proteins as important in male fertility. Such repurposing of existing therapeutics thus creates direct routes to probing in vivo function. The success of this strategy suggests a general approach to discovering 'carbohydrate-active' partners in biology.
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Affiliation(s)
- Isa N. Cruz
- Department of Pharmaceutical & Biological Chemistry, UCL School of Pharmacy, University College London, 29/39 Brunswick Square, London, WC1N 1AX, UK
| | - Conor S. Barry
- Department of Chemistry, Chemistry Research Laboratory, Oxford University, Mansfield Road, Oxford, OX1 3TA, UK
| | - Holger B. Kramer
- Department of Physiology, Anatomy and Genetics, University of Oxford, South Parks Road, Oxford, OX1 3PT, UK
| | - C. Celeste Chuang
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, OX1 3QT, UK
| | - Sarah Lloyd
- MRC Prion Unit, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | | | - Frances M. Platt
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, OX1 3QT, UK
| | - Min Yang
- Department of Pharmaceutical & Biological Chemistry, UCL School of Pharmacy, University College London, 29/39 Brunswick Square, London, WC1N 1AX, UK
| | - Benjamin G. Davis
- Department of Chemistry, Chemistry Research Laboratory, Oxford University, Mansfield Road, Oxford, OX1 3TA, UK
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7
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Barker MK, Rose DR. Specificity of Processing α-glucosidase I is guided by the substrate conformation: crystallographic and in silico studies. J Biol Chem 2013; 288:13563-74. [PMID: 23536181 DOI: 10.1074/jbc.m113.460436] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND The enzyme “GluI” is key to the synthesis of critical glycoproteins in the cell. RESULTS We have determined the structure of GluI, and modeled binding with its unique sugar substrate. CONCLUSION The specificity of this interaction derives from a unique conformation of the substrate. SIGNIFICANCE Understanding the mechanism of the enzyme is of basic importance and relevant to potential development of antiviral inhibitors. Processing α-glucosidase I (GluI) is a key member of the eukaryotic N-glycosylation processing pathway, selectively catalyzing the first glycoprotein trimming step in the endoplasmic reticulum. Inhibition of GluI activity impacts the infectivity of enveloped viruses; however, despite interest in this protein from a structural, enzymatic, and therapeutic standpoint, little is known about its structure and enzymatic mechanism in catalysis of the unique glycan substrate Glc3Man9GlcNAc2. The first structural model of eukaryotic GluI is here presented at 2-Å resolution. Two catalytic residues are proposed, mutations of which result in catalytically inactive, properly folded protein. Using Autodocking methods with the known substrate and inhibitors as ligands, including a novel inhibitor characterized in this work, the active site of GluI was mapped. From these results, a model of substrate binding has been formulated, which is most likely conserved in mammalian GluI.
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Affiliation(s)
- Megan K Barker
- Department of Medical Biophysics, University of Toronto, Ontario Cancer Institute, Princess Margaret Hospital, Toronto, Ontario M5G 2M9, Canada.
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8
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Barker MK, Wilkinson BL, Faridmoayer A, Scaman CH, Fairbanks AJ, Rose DR. Production and crystallization of processing α-glucosidase I: Pichia pastoris expression and a two-step purification toward structural determination. Protein Expr Purif 2011; 79:96-101. [PMID: 21640829 DOI: 10.1016/j.pep.2011.05.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2011] [Revised: 05/19/2011] [Accepted: 05/20/2011] [Indexed: 12/17/2022]
Abstract
Eukaryotic N-glycoprotein processing in the endoplasmic reticulum begins with the catalytic action of processing α-glucosidase I (αGlu). αGlu trims the terminal glucose from nascent glycoproteins in an inverting-mechanism glycoside hydrolysis reaction. αGlu has been studied in terms of kinetic parameters and potential key residues; however, the active site is unknown. A structural model would yield important insights into the reaction mechanism. A model would also be useful in developing specific therapeutics, as αGlu is a viable drug target against viruses with glycosylated envelope proteins. However, due to lack of a high-yielding overexpression and purification scheme, no eukaryotic structural model of αGlu has been determined. To address this issue, we overexpressed the Saccharomyces cerevisiae soluble αGlu, Cwht1p, in the host Pichia pastoris. It was purified in a simple two-step protocol, with a final yield of 4.2mg Cwht1p per liter of growth culture. To test catalytic activity, we developed a modified synthesis of a tetrasaccharide substrate, Glc(3)ManOMe. Cwht1p with Glc(3)ManOMe shows a K(m) of 1.26 mM. Cwht1p crystals were grown and subjected to X-ray irradiation, giving a complete diffraction dataset to 2.04 Å resolution. Work is ongoing to obtain phases so that we may further understand this fundamental member of the N-glycosylation pathway through the discovery of its molecular structure.
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Affiliation(s)
- Megan K Barker
- Department of Medical Biophysics, University of Toronto, Toronto, Canada
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9
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Tonozuka T, Miyazaki T, Nishikawa A. Structural Similarity between a Starch-hydrolyzing Enzyme and an N-Glycan-Hydrolyzing Enzyme: Exohydrolases Cleaving α-1,X-Glucosidic Linkages to Produce β-Glucose. TRENDS GLYCOSCI GLYC 2011. [DOI: 10.4052/tigg.23.93] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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10
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Carvalho AFA, Boscolo M, da Silva R, Ferreira H, Gomes E. Purification and characterization of the α-glucosidase produced by thermophilic fungus Thermoascus aurantiacus CBMAI 756. J Microbiol 2010; 48:452-9. [DOI: 10.1007/s12275-010-9319-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2009] [Accepted: 04/23/2010] [Indexed: 10/19/2022]
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11
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Mora-Montes HM, Ponce-Noyola P, Villagómez-Castro JC, Gow NA, Flores-Carreón A, López-Romero E. Protein glycosylation in Candida. Future Microbiol 2010; 4:1167-83. [PMID: 19895219 DOI: 10.2217/fmb.09.88] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Candidiasis is a significant cause of invasive human mycosis with associated mortality rates that are equivalent to, or worse than, those cited for most cases of bacterial septicemia. As a result, considerable efforts are being made to understand how the fungus invades host cells and to identify new targets for fungal chemotherapy. This has led to an increasing interest in Candida glycobiology, with an emphasis on the identification of enzymes essential for glycoprotein and adhesion metabolism, and the role of N- and O-linked glycans in host recognition and virulence. Here, we refer to studies dealing with the identification and characterization of enzymes such as dolichol phosphate mannose synthase, dolichol phosphate glucose synthase and processing glycosidases and synthesis, structure and recognition of mannans and discuss recent findings in the context of Candida albicans pathogenesis.
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12
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Kurakata Y, Uechi A, Yoshida H, Kamitori S, Sakano Y, Nishikawa A, Tonozuka T. Structural insights into the substrate specificity and function of Escherichia coli K12 YgjK, a glucosidase belonging to the glycoside hydrolase family 63. J Mol Biol 2008; 381:116-28. [PMID: 18586271 DOI: 10.1016/j.jmb.2008.05.061] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2008] [Revised: 05/16/2008] [Accepted: 05/21/2008] [Indexed: 10/22/2022]
Abstract
Proteins belonging to the glycoside hydrolase family 63 (GH63) are found in bacteria, archaea, and eukaryotes. Eukaryotic GH63 proteins are processing *-glucosidase I enzymes that hydrolyze an oligosaccharide precursor of eukaryotic N-linked glycoproteins. In contrast, the functions of the bacterial and archaeal GH63 proteins are unclear. Here we determined the crystal structure of a bacterial GH63 enzyme, Escherichia coli K12 YgjK, at 1.78 A resolution and investigated some properties of the enzyme. YgjK consists of the N-domain and the A-domain, joined by a linker region. The N-domain is composed of 18 antiparallel beta-strands and is classified as a super-beta-sandwich. The A-domain contains 16 *-helices, 12 of which form an (*/*)(6)-barrel; the remaining 4 *-helices are found in an extra structural unit that we designated as the A'-region. YgjK, a member of the glycoside hydrolase clan GH-G, shares structural similarity with glucoamylase (GH15) and chitobiose phosphorylase (GH94) [corrected] both of which belong to clan GH-L or GH-L-like [corrected] In crystal structures of YgjK in complex with glucose, mannose, and galactose, all of the glucose, mannose, and galactose units were located in the catalytic cleft. YgjK showed the highest activity for the *-1,3-glucosidic linkage of nigerose, but also hydrolyzed trehalose, kojibiose, and maltooligosaccharides from maltose to maltoheptaose, although the activities were low. These findings suggest that YgjK is a glucosidase with relaxed specificity for sugars.
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Affiliation(s)
- Yuma Kurakata
- Department of Applied Biological Science, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-Cho, Fuchu, Tokyo 183-8509, Japan
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13
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Mora-Montes HM, López-Romero E, Zinker S, Ponce-Noyola P, Flores-Carreón A. Conversion of α1,2-mannosidase E-I from Candida albicans to α1,2-mannosidase E-II by limited proteolysis. Antonie van Leeuwenhoek 2007; 93:61-9. [PMID: 17588125 DOI: 10.1007/s10482-007-9179-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2007] [Accepted: 05/23/2007] [Indexed: 10/23/2022]
Abstract
Previous studies demonstrated the presence in Candida albicans ATCC 26555 of two soluble alpha1,2-mannosidases: E-I and E-II. In contrast, in the C. albicans CAI-4 mutant only E-I was detected and it could be processed by a membrane-bound proteolytic activity from the ATCC 26555 strain, generating an active 43 kDa polypeptide. Here, alpha1,2-mannosidase E-I from strain ATCC 26555 was purified by conventional methods of protein isolation and affinity chromatography in Concanavalin A-Sepharose 4B. Analytical electrophoresis of the purified enzyme revealed two polypeptides of 52 and 23 kDa, the former being responsible for enzyme activity as revealed by zymogram analysis. Time course proteolysis with an aspartyl protease from Aspergillus saitoi, converted alpha1,2-mannosidase E-I into an active polypeptide of 43 kDa which trimmed Man(9)GlcNAc(2), generating Man(8)GlcNAc(2) isomer B and mannose. Trimming was inhibited preferentially by 1-deoxymannojirimycin. Both, the molecular mass and the enzyme properties of the proteolytic product were identical to those described for alpha1,2-mannosidase E-II therefore supporting the notion that E-I is the precursor of E-II.
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Affiliation(s)
- Héctor Manuel Mora-Montes
- Instituto de Investigación en Biología Experimental, Facultad de Química, Universidad de Guanajuato, Apartado postal 187, Guanajuato, Gto, CP 36000, Mexico
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14
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Stable expression of glucoamylase gene in industrial strain ofSaccharomyces pastorianus with less diacetyl produced. ANN MICROBIOL 2007. [DOI: 10.1007/bf03175212] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
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15
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Faridmoayer A, Scaman CH. Truncations and functional carboxylic acid residues of yeast processing alpha-glucosidase I. Glycoconj J 2007; 24:429-37. [PMID: 17458696 DOI: 10.1007/s10719-007-9035-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2006] [Revised: 02/25/2007] [Accepted: 04/04/2007] [Indexed: 11/24/2022]
Abstract
Yeast alpha-glucosidase I (Cwh41p) encoded by CWH41 is an endoplasmic reticulum (ER) membrane-bound glycoprotein (833 residues), which plays an important role in the early steps of the N-glycosylation pathway. In this study functional expression of three truncated fragments of Cwh41p, all containing the catalytic region, was investigated. Cwht1p (E35-F833), with deletion of the N-terminus and transmembrane domain, was expressed as a catalytically active fragment while R320-F833(Cwht2p) and M526-F833 (Cwht3p) were not detected. Significantly higher glucosidase I activity was found in a soluble extract from yeast overexpressing CWHT1 (1,400 U/g biomass) than yeast overexpressing CWH41 (300 U/g biomass). Cwht1p was purified as a soluble 94 kDa non-glycosylated protein with a specific activity (3,600 U/mg protein) comparable to that of the soluble alpha-glucosidase I (3000 U/mg protein). These findings indicate that the active conformation of the enzyme is not dependent on protein glycosylation and suggest that the M1-I28 region of Cwh41p carries an ER-targeting signal sequence. In addition, two highly conserved carboxylic acid residues, E580 and D584 of Cwht1p (corresponding to E613 and D617 of Cwh41p), located within the catalytic domain of yeast enzyme were subjected to mutation. Substitution of each residue with Ala resulted in low expression and undetectable glucosidase I activity. These findings indicate that E613 and D617 play a crucial role in maintaining alpha-glucosidase I activity.
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Affiliation(s)
- Amirreza Faridmoayer
- Food, Nutrition, and Health Program, University of British Columbia, Vancouver, V6T 1Z4, Canada
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16
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Faridmoayer A, Scaman CH. Binding residues and catalytic domain of soluble Saccharomyces cerevisiae processing alpha-glucosidase I. Glycobiology 2005; 15:1341-8. [PMID: 16014748 DOI: 10.1093/glycob/cwj009] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Alpha-glucosidase I initiates the trimming of newly assembled N-linked glycoproteins in the lumen of the endoplasmic reticulum (ER). Site-specific chemical modification of the soluble alpha-glucosidase I from yeast using diethylpyrocarbonate (DEPC) and tetranitromethane (TNM) revealed that histidine and tyrosine are involved in the catalytic activity of the enzyme, as these residues could be protected from modification using the inhibitor deoxynojirimycin. Deoxynojirimycin could not prevent inactivation of enzyme treated with N-bromosuccinimide (NBS) used to modify tryptophan residues. Therefore, the binding mechanism of yeast enzyme contains different amino acid residues compared to its mammalian counterpart. Catalytically active polypeptides were isolated from endogenous proteolysis and controlled trypsin hydrolysis of the enzyme. A 37-kDa nonglycosylated polypeptide was isolated as the smallest active fragment from both digests, using affinity chromatography with inhibitor-based resins (N-methyl-N-59-carboxypentyl- and N-59-carboxypentyl-deoxynojirimycin). N-terminal sequencing confirmed that the catalytic domain of the enzyme is located at the C-terminus. The hydrolysis sites were between Arg(521) and Thr(522) for endogenous proteolysis and residues Lys(524) and Phe(525) for the trypsin-generated peptide. This 37-kDa polypeptide is 1.9 times more active than the 98-kDa protein when assayed with the synthetic trisaccharide, alpha-D-Glc1,2alpha-D-Glc1,3alpha-D-Glc-O(CH2)(8)COOCH(3), and is not glycosylated. Identification of this relatively small fragment with catalytic activity will allow mechanistic studies to focus on this critical region and raises interesting questions about the relationship between the catalytic region and the remaining polypeptide.
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Affiliation(s)
- Amirreza Faridmoayer
- Food, Nutrition, and Health, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4
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