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Garcia CA, Gardner JG. Bacterial α-diglucoside metabolism: perspectives and potential for biotechnology and biomedicine. Appl Microbiol Biotechnol 2021; 105:4033-4052. [PMID: 33961116 PMCID: PMC8237927 DOI: 10.1007/s00253-021-11322-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 04/20/2021] [Accepted: 04/26/2021] [Indexed: 12/16/2022]
Abstract
In a competitive microbial environment, nutrient acquisition is a major contributor to the survival of any individual bacterial species, and the ability to access uncommon energy sources can provide a fitness advantage. One set of soluble carbohydrates that have attracted increased attention for use in biotechnology and biomedicine is the α-diglucosides. Maltose is the most well-studied member of this class; however, the remaining four less common α-diglucosides (trehalose, kojibiose, nigerose, and isomaltose) are increasingly used in processed food and fermented beverages. The consumption of trehalose has recently been shown to be a contributing factor in gut microbiome disease as certain pathogens are using α-diglucosides to outcompete native gut flora. Kojibiose and nigerose have also been examined as potential prebiotics and alternative sweeteners for a variety of foods. Compared to the study of maltose metabolism, our understanding of the synthesis and degradation of uncommon α-diglucosides is lacking, and several fundamental questions remain unanswered, particularly with regard to the regulation of bacterial metabolism for α-diglucosides. Therefore, this minireview attempts to provide a focused analysis of uncommon α-diglucoside metabolism in bacteria and suggests some future directions for this research area that could potentially accelerate biotechnology and biomedicine developments. KEY POINTS: • α-diglucosides are increasingly important but understudied bacterial metabolites. • Kinetically superior α-diglucoside enzymes require few amino acid substitutions. • In vivo studies are required to realize the biotechnology potential of α-diglucosides.
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Affiliation(s)
- Cecelia A Garcia
- Department of Biological Sciences, University of Maryland-Baltimore County, Baltimore, MD, USA
| | - Jeffrey G Gardner
- Department of Biological Sciences, University of Maryland-Baltimore County, Baltimore, MD, USA.
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2
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Dong Z, Tang C, Lu Y, Yao L, Kan Y. Microbial Oligo‐α‐1,6‐Glucosidase: Current Developments and Future Perspectives. STARCH-STARKE 2019. [DOI: 10.1002/star.201900172] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Zixing Dong
- Henan Provincial Engineering Laboratory of Insect Bio‐reactor and Henan Key Laboratory of Ecological Security for Water Region of Mid‐line of South‐to‐NorthNanyang Normal University Nanyang 473061 P. R. China
| | - Cunduo Tang
- Henan Provincial Engineering Laboratory of Insect Bio‐reactor and Henan Key Laboratory of Ecological Security for Water Region of Mid‐line of South‐to‐NorthNanyang Normal University Nanyang 473061 P. R. China
| | - Yunfeng Lu
- School of Life Science and TechnologyNanyang Normal University Nanyang 473061 P. R. China
| | - Lunguang Yao
- Henan Provincial Engineering Laboratory of Insect Bio‐reactor and Henan Key Laboratory of Ecological Security for Water Region of Mid‐line of South‐to‐NorthNanyang Normal University Nanyang 473061 P. R. China
| | - Yunchao Kan
- Henan Provincial Engineering Laboratory of Insect Bio‐reactor and Henan Key Laboratory of Ecological Security for Water Region of Mid‐line of South‐to‐NorthNanyang Normal University Nanyang 473061 P. R. China
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3
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Dong Z, Hao X, Pokhrel DS, Chen X, Liu X, Mchunu NP, Permaul K, Singh S, Niu D, Wang Z. Molecular cloning and biochemical characterization of two novel oligo-1,6-glucosidases fromBacillus mycoidesandThermomyces lanuginosus. STARCH-STARKE 2017. [DOI: 10.1002/star.201700093] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Zixing Dong
- Key Laboratory of Industrial Fermentation Microbiology; Ministry of Education; College of Biotechnology; Tianjin University of Science & Technology; Tianjin P.R. China
- College of Chemical Engineering and Materials Science; Tianjin University of Science & Technology; Tianjin P.R. China
| | - Xiaoming Hao
- Key Laboratory of Industrial Fermentation Microbiology; Ministry of Education; College of Biotechnology; Tianjin University of Science & Technology; Tianjin P.R. China
| | - Daman S. Pokhrel
- Key Laboratory of Industrial Fermentation Microbiology; Ministry of Education; College of Biotechnology; Tianjin University of Science & Technology; Tianjin P.R. China
| | - Xiaoling Chen
- Key Laboratory of Industrial Fermentation Microbiology; Ministry of Education; College of Biotechnology; Tianjin University of Science & Technology; Tianjin P.R. China
| | - Xiaoguang Liu
- College of Chemical Engineering and Materials Science; Tianjin University of Science & Technology; Tianjin P.R. China
| | - Nokuthula P. Mchunu
- Faculty of Applied Sciences; Department of Biotechnology & Food Technology; Durban University of Technology; Durban South Africa
| | - Kugenthiren Permaul
- Faculty of Applied Sciences; Department of Biotechnology & Food Technology; Durban University of Technology; Durban South Africa
| | - Suren Singh
- Faculty of Applied Sciences; Department of Biotechnology & Food Technology; Durban University of Technology; Durban South Africa
| | - Dandan Niu
- College of Biological Science and Technology; Fuzhou University; Fuzhou P.R. China
| | - Zhengxiang Wang
- Key Laboratory of Industrial Fermentation Microbiology; Ministry of Education; College of Biotechnology; Tianjin University of Science & Technology; Tianjin P.R. China
- College of Chemical Engineering and Materials Science; Tianjin University of Science & Technology; Tianjin P.R. China
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Ahmad N, Mehboob S, Rashid N. Starch-processing enzymes — emphasis on thermostable 4-α-glucanotransferases. Biologia (Bratisl) 2015. [DOI: 10.1515/biolog-2015-0087] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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5
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Similarities and differences in the biochemical and enzymological properties of the four isomaltases from Saccharomyces cerevisiae. FEBS Open Bio 2014; 4:200-12. [PMID: 24649402 PMCID: PMC3953731 DOI: 10.1016/j.fob.2014.02.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Revised: 01/29/2014] [Accepted: 02/10/2014] [Indexed: 11/21/2022] Open
Abstract
Isomaltases (Imap) preferably cleave α-(1,6) bonds, yet show clear substrate ambiguity. With only 3 different aa, Ima3p activities and thermostability diverge from Ima2p. The most distant protein, Ima5p, is extremely sensitive to temperature. Ima5p nevertheless displays most of the same catalytic properties as Ima1p and Ima2p. Ima5p challenges previous conclusions about specific aa needs for the active site.
The yeast Saccharomyces cerevisiae IMA multigene family encodes four isomaltases sharing high sequence identity from 65% to 99%. Here, we explore their functional diversity, with exhaustive in-vitro characterization of their enzymological and biochemical properties. The four isoenzymes exhibited a preference for the α-(1,6) disaccharides isomaltose and palatinose, with Michaëlis–Menten kinetics and inhibition at high substrates concentration. They were also able to hydrolyze trisaccharides bearing an α-(1,6) linkage, but also α-(1,2), α-(1,3) and α-(1,5) disaccharides including sucrose, highlighting their substrate ambiguity. While Ima1p and Ima2p presented almost identical characteristics, our results nevertheless showed many singularities within this protein family. In particular, Ima3p presented lower activities and thermostability than Ima2p despite only three different amino acids between the sequences of these two isoforms. The Ima3p_R279Q variant recovered activity levels of Ima2p, while the Leu-to-Pro substitution at position 240 significantly increased the stability of Ima3p and supported the role of prolines in thermostability. The most distant protein, Ima5p, presented the lowest optimal temperature and was also extremely sensitive to temperature. Isomaltose hydrolysis by Ima5p challenged previous conclusions about the requirement of specific amino acids for determining the specificity for α-(1,6) substrates. We finally found a mixed inhibition by maltose for Ima5p while, contrary to a previous work, Ima1p inhibition by maltose was competitive at very low isomaltose concentrations and uncompetitive as the substrate concentration increased. Altogether, this work illustrates that a gene family encoding proteins with strong sequence similarities can lead to enzyme with notable differences in biochemical and enzymological properties.
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6
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Identification of critical amino acid residues for chloride binding of Bacillus licheniformis trehalose-6-phosphate hydrolase. Biologia (Bratisl) 2013. [DOI: 10.2478/s11756-013-0290-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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7
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Woys AM, Almeida AM, Wang L, Chiu CC, McGovern M, de Pablo JJ, Skinner JL, Gellman SH, Zanni MT. Parallel β-sheet vibrational couplings revealed by 2D IR spectroscopy of an isotopically labeled macrocycle: quantitative benchmark for the interpretation of amyloid and protein infrared spectra. J Am Chem Soc 2012; 134:19118-28. [PMID: 23113791 DOI: 10.1021/ja3074962] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Infrared spectroscopy is playing an important role in the elucidation of amyloid fiber formation, but the coupling models that link spectra to structure are not well tested for parallel β-sheets. Using a synthetic macrocycle that enforces a two stranded parallel β-sheet conformation, we measured the lifetimes and frequency for six combinations of doubly (13)C═(18)O labeled amide I modes using 2D IR spectroscopy. The average vibrational lifetime of the isotope labeled residues was 550 fs. The frequencies of the labels ranged from 1585 to 1595 cm(-1), with the largest frequency shift occurring for in-register amino acids. The 2D IR spectra of the coupled isotope labels were calculated from molecular dynamics simulations of a series of macrocycle structures generated from replica exchange dynamics to fully sample the conformational distribution. The models used to simulate the spectra include through-space coupling, through-bond coupling, and local frequency shifts caused by environment electrostatics and hydrogen bonding. The calculated spectra predict the line widths and frequencies nearly quantitatively. Historically, the characteristic features of β-sheet infrared spectra have been attributed to through-space couplings such as transition dipole coupling. We find that frequency shifts of the local carbonyl groups due to nearest neighbor couplings and environmental factors are more important, while the through-space couplings dictate the spectral intensities. As a result, the characteristic absorption spectra empirically used for decades to assign parallel β-sheet secondary structure arises because of a redistribution of oscillator strength, but the through-space couplings do not themselves dramatically alter the frequency distribution of eigenstates much more than already exists in random coil structures. Moreover, solvent exposed residues have amide I bands with >20 cm(-1) line width. Narrower line widths indicate that the amide I backbone is solvent protected inside the macrocycle. This work provides calculated and experimentally verified couplings for parallel β-sheets that can be used in structure-based models to simulate and interpret the infrared spectra of β-sheet containing proteins and protein assemblies, such as amyloid fibers.
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Affiliation(s)
- Ann Marie Woys
- Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706, USA
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8
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Hondoh H, Otsuka-Rachi H, Saburi W, Mori H, Okuyama M, Kimura A. Structural Comparison of <i>Streptococcus mutans</i> Dextran Glucosidase with Glucoside Hydrolases in GH13. J Appl Glycosci (1999) 2009. [DOI: 10.5458/jag.56.111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Affiliation(s)
- Hironori Hondoh
- Division of Applied Bioscience Research, Faculty of Agriculture, Hokkaido University
| | - Hiroaki Otsuka-Rachi
- Division of Applied Bioscience Research, Faculty of Agriculture, Hokkaido University
| | - Wataru Saburi
- Division of Applied Bioscience Research, Faculty of Agriculture, Hokkaido University
| | - Haruhide Mori
- Division of Applied Bioscience Research, Faculty of Agriculture, Hokkaido University
| | - Masayuki Okuyama
- Division of Applied Bioscience Research, Faculty of Agriculture, Hokkaido University
| | - Atsuo Kimura
- Division of Applied Bioscience Research, Faculty of Agriculture, Hokkaido University
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9
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Hondoh H, Saburi W, Mori H, Okuyama M, Nakada T, Matsuura Y, Kimura A. Substrate Recognition Mechanism of α-1,6-Glucosidic Linkage Hydrolyzing Enzyme, Dextran Glucosidase from Streptococcus mutans. J Mol Biol 2008; 378:913-22. [DOI: 10.1016/j.jmb.2008.03.016] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2007] [Revised: 03/07/2008] [Accepted: 03/10/2008] [Indexed: 11/16/2022]
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10
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Nishio T, Hakamata W, Ogawa M, Nakajima K, Matsuishi Y, Kawachi R, Oku T. Investigations of a Useful .ALPHA.-Glycosidase for the Enzymatic Synthesis of Rare Sugar Oligosaccharides. J Appl Glycosci (1999) 2005. [DOI: 10.5458/jag.52.153] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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11
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Janecek S, Svensson B, MacGregor EA. Relation between domain evolution, specificity, and taxonomy of the alpha-amylase family members containing a C-terminal starch-binding domain. EUROPEAN JOURNAL OF BIOCHEMISTRY 2003; 270:635-45. [PMID: 12581203 DOI: 10.1046/j.1432-1033.2003.03404.x] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The alpha-amylase family (glycoside hydrolase family 13; GH 13) contains enzymes with approximately 30 specificities. Six types of enzyme from the family can possess a C-terminal starch-binding domain (SBD): alpha-amylase, maltotetraohydrolase, maltopentaohydrolase, maltogenic alpha-amylase, acarviose transferase, and cyclodextrin glucanotransferase (CGTase). Such enzymes are multidomain proteins and those that contain an SBD consist of four or five domains, the former enzymes being mainly hydrolases and the latter mainly transglycosidases. The individual domains are labelled A [the catalytic (beta/alpha)8-barrel], B, C, D and E (SBD), but D is lacking from the four-domain enzymes. Evolutionary trees were constructed for domains A, B, C and E and compared with the 'complete-sequence tree'. The trees for domains A and B and the complete-sequence tree were very similar and contain two main groups of enzymes, an amylase group and a CGTase group. The tree for domain C changed substantially, the separation between the amylase and CGTase groups being shortened, and a new border line being suggested to include the Klebsiella and Nostoc CGTases (both four-domain proteins) with the four-domain amylases. In the 'SBD tree' the border between hydrolases (mainly alpha-amylases) and transglycosidases (principally CGTases) was not readily defined, because maltogenic alpha-amylase, acarviose transferase, and the archaeal CGTase clustered together at a distance from the main CGTase cluster. Moreover the four-domain CGTases were rooted in the amylase group, reflecting sequence relationships for the SBD. It appears that with respect to the SBD, evolution in GH 13 shows a transition in the segment of the proteins C-terminal to the catalytic (beta/alpha)8-barrel(domain A).
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Affiliation(s)
- Stefan Janecek
- Institute of Molecular Biology, Slovak Academy of Sciences, Bratislava, Slovakia.
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12
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Zhang D, Li X, Zhang LH. Isomaltulose synthase from Klebsiella sp. strain LX3: gene cloning and characterization and engineering of thermostability. Appl Environ Microbiol 2002; 68:2676-82. [PMID: 12039719 PMCID: PMC123955 DOI: 10.1128/aem.68.6.2676-2682.2002] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2001] [Accepted: 03/20/2002] [Indexed: 11/20/2022] Open
Abstract
The gene (palI) encoding isomaltulose synthase (PalI) from a soil bacterial isolate, Klebsiella sp. strain LX3, was cloned and characterized. PalI converts sucrose into isomaltulose, trehalulose, and trace amounts of glucose and fructose. Sequence domain analysis showed that PalI contains an alpha-amylase domain and (beta/alpha)(8)-barrel structures, suggesting that it belongs to the alpha-amylase family. Sequence alignment indicated that the five amino acid residues of catalytic importance in alpha-amylases and glucosyltransferases (Asp(241), Glu(295), Asp(369), His(145), and His(368)) are conserved in PalI. Purified recombinant PalI displayed high catalytic efficiency, with a Km of 54.6 +/- 1.7 mM for sucrose, and maximum activity (approximately 328.0 +/- 2.5 U/mg) at pH 6.0 and 35 degrees C. PalI activity was strongly inhibited by Fe3+ and Hg2+ and was enhanced by Mn2+ and Mg2+. The half-life of PalI was 1.8 min at 50 degrees C. Replacement of selected amino acid residues by proline significantly increased the thermostability of PalI. Simultaneous replacement of Glu(498) and Arg(310) with proline resulted in an 11-fold increase in the half-life of PalI at 50 degrees C.
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Affiliation(s)
- Daohai Zhang
- Laboratory of Biosignals and Bioengineering, Institute of Molecular Agrobiology, Singapore 117604
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13
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Okuyama M, Okuno A, Shimizu N, Mori H, Kimura A, Chiba S. Carboxyl group of residue Asp647 as possible proton donor in catalytic reaction of alpha-glucosidase from Schizosaccharomyces pombe. EUROPEAN JOURNAL OF BIOCHEMISTRY 2001; 268:2270-80. [PMID: 11298744 DOI: 10.1046/j.1432-1327.2001.02104.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
cDNA encoding Schizosaccharomyces pombe alpha-glucosidase was cloned from a library constructed from mRNA of the fission yeast, and expressed in Saccharomyces cerevisiae. The cDNA, 4176 bp in length, included a single ORF composed of 2910 bp encoding a polypeptide of 969 amino-acid residues with M(r) 106 138. The deduced amino-acid sequence showed a high homology to those of alpha-glucosidases from molds, plants and mammals. Therefore, the enzyme was categorized into the alpha-glucosidase family II. By site-directed mutagenesis, Asp481, Glu484 and Asp647 residues were confirmed to be essential in the catalytic reaction. The carboxyl group (-COOH) of the Asp647 residue was for the first time shown to be the most likely proton donor acting as the acid catalyst in the alpha-glucosidase of family II. Studies with the chemical modifier conduritol B epoxide suggested that the carboxylate group (-COO-) of the Asp481 residue was the catalytic nucleophile, although the role of the Glu484 residue remains obscure.
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Affiliation(s)
- M Okuyama
- Division of Applied Bioscience, Graduate School of Agriculture, Hokkaido University, Sapporo, Japan
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MacGregor EA, Janecek S, Svensson B. Relationship of sequence and structure to specificity in the alpha-amylase family of enzymes. BIOCHIMICA ET BIOPHYSICA ACTA 2001; 1546:1-20. [PMID: 11257505 DOI: 10.1016/s0167-4838(00)00302-2] [Citation(s) in RCA: 454] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The hydrolases and transferases that constitute the alpha-amylase family are multidomain proteins, but each has a catalytic domain in the form of a (beta/alpha)(8)-barrel, with the active site being at the C-terminal end of the barrel beta-strands. Although the enzymes are believed to share the same catalytic acids and a common mechanism of action, they have been assigned to three separate families - 13, 70 and 77 - in the classification scheme for glycoside hydrolases and transferases that is based on amino acid sequence similarities. Each enzyme has one glutamic acid and two aspartic acid residues necessary for activity, while most enzymes of the family also contain two histidine residues critical for transition state stabilisation. These five residues occur in four short sequences conserved throughout the family, and within such sequences some key amino acid residues are related to enzyme specificity. A table is given showing motifs distinctive for each specificity as extracted from 316 sequences, which should aid in identifying the enzyme from primary structure information. Where appropriate, existing problems with identification of some enzymes of the family are pointed out. For enzymes of known three-dimensional structure, action is discussed in terms of molecular architecture. The sequence-specificity and structure-specificity relationships described may provide useful pointers for rational protein engineering.
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Affiliation(s)
- E A MacGregor
- Department of Chemistry, University of Manitoba, Winnepeg, Manitoba R3T 2N2, Canada
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Janda L, Damborský J, Petrícek M, Spízek J, Tichý P. Molecular characterization of the Thermomonospora curvata aglA gene encoding a thermotolerant alpha-1,4-glucosidase. J Appl Microbiol 2000; 88:773-83. [PMID: 10792537 DOI: 10.1046/j.1365-2672.2000.01019.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The cloning, sequencing and structural characterization of a gene encoding a thermostable alpha-1,4-glucosidase from Thermomonospora curvata is described. DNA sequence analysis revealed four open reading frames designated aglA, aglR, aglE and aglF. The aglA gene encodes a thermostable alpha-1,4-glucosidase from T. curvata and is situated between two genes, aglR and aglE. Genes aglA, aglE and aglF are transcribed in the same direction, while aglR is transcribed in the opposite direction. By comparing the amino acid sequence of the alpha-1,4-glucosidase from T. curvata with other alpha-glucanases, it appears that the enzyme is a member of the alpha-amylase family. The proteins of this family have an (alpha/beta)8 barrel super secondary structure. The topology of the alpha-1,4-glucosidase was predicted by computer-assisted analysis. The topology of the secondary structures of the alpha-1,4-glucosidase resembles the structure of barley alpha-amylase, but the primary structure resembles most closely the oligo-1,6-glucosidase from Bacillus cereus. Putative catalytic residues (D221, E281 and D343) and calcium binding residues (N116, E179, D191, H224 or G225) are proposed.
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Affiliation(s)
- L Janda
- Institute of Microbiology, Academy of Sciences of the Czech Republic, Prague and Laboratory of Biomolecular Structure and Dynamics, Faculty of Science, Masaryk University, Brno, Czech Republic
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Przylas I, Tomoo K, Terada Y, Takaha T, Fujii K, Saenger W, Sträter N. Crystal structure of amylomaltase from thermus aquaticus, a glycosyltransferase catalysing the production of large cyclic glucans. J Mol Biol 2000; 296:873-86. [PMID: 10677288 DOI: 10.1006/jmbi.1999.3503] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Amylomaltase is involved in the metabolism of starch, one of the most important polysaccharides in nature. A unique feature of amylomaltase is its ability to catalyze the formation of cyclic amylose. In contrast to the well studied cyclodextrin glucanotransferases (CGTases), which synthesize cycloamylose with a ring size (degree of polymerization or DP) of 6-8, the amylomaltase from Thermus aquaticus produces cycloamyloses with a DP of 22 and higher. The crystal structure of amylomaltase from Thermus aquaticus was determined to 2.0 A resolution. It is a member of the alpha-amylase superfamily of enzymes, whose core structure consists of a (beta, alpha)(8) barrel. In amylomaltase, the 8-fold symmetry of this barrel is disrupted by several insertions between the barrel strands. The largest insertions are between the third and fifth barrel strands, where two insertions form subdomain B1, as well as between the second and third barrel strands, forming the alpha-helical subdomain B2. Whereas part of subdomain B1 is also present in other enzyme structures of the alpha-amylase superfamily, subdomain B2 is unique to amylomaltase. Remarkably, the C-terminal domain C, which is present in all related enzymes of the alpha-amylase family, is missing in amylomaltase. Amylomaltase shows a similar arrangement of the catalytic side-chains (two Asp residues and one Glu residue) as in previously characterized members of the alpha-amylase superfamily, indicating similar mechanisms of the glycosyl transfer reaction. In amylomaltase, a conserved loop of around eight amino acid residues is partially shielding the active center. This loop, which is well conserved among other amylomaltases, may sterically hinder the formation of small cyclic products.
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Affiliation(s)
- I Przylas
- Freie Universität Berlin, Institut für Chemie, Abteilung Kristallographie, Takustrasse 6, Berlin, 14195, Germany
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17
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Katsuya Y, Mezaki Y, Kubota M, Matsuura Y. Three-dimensional structure of Pseudomonas isoamylase at 2.2 A resolution. J Mol Biol 1998; 281:885-97. [PMID: 9719642 DOI: 10.1006/jmbi.1998.1992] [Citation(s) in RCA: 109] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The three-dimensional structure of isoamylase from Pseudomonas amyloderamosa, which hydrolyzes alpha-1,6-glucosidic linkages of amylopectin and glycogen, has been determined by X-ray structure analysis. The enzyme has 750 amino acid residues and a molecular mass of 80 kDa, and it can be crystallized from ammonium sulfate solution. The structure was elucidated by the multiple isomorphous replacement method and refined at 2.2 A resolution, resulting in a final R-factor of 0.161 for significant reflections with a root-mean-square deviation from ideality in bond lengths of 0.009 A. The analysis revealed that in the N-terminal region, isoamylase has a novel extra domain that we call domain N, whose three-dimensional structure has not so far been reported. It has a (beta/alpha)8-barrel-type supersecondary structure in the catalytic domain common to the alpha-amylase family enzymes, though the barrel is incomplete, with a deletion of an alpha-helix between the fifth and sixth beta-strands. A long excursed region is present between the third beta-strand and the third alpha-helix of the barrel but, in contrast to the so-called domain B that has been identified in the other enzymes of alpha-amylase family, it cannot be considered to be an independent domain, because this loop forms a globular cluster together with the loop between the fourth beta-strand and the fourth alpha-helix. Isoamylase contains a bound calcium ion, but this is not in the same position as the conserved calcium ion that has been reported in other alpha-amylase family enzymes.
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Affiliation(s)
- Y Katsuya
- Hyogo Prefectural Institute of Industrial Research, Suma-ku, Kobe, 654-0037, Japan.
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18
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19
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Janecek S. alpha-Amylase family: molecular biology and evolution. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 1997; 67:67-97. [PMID: 9401418 DOI: 10.1016/s0079-6107(97)00015-1] [Citation(s) in RCA: 146] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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20
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Devulapalle KS, Goodman SD, Gao Q, Hemsley A, Mooser G. Knowledge-based model of a glucosyltransferase from the oral bacterial group of mutans streptococci. Protein Sci 1997; 6:2489-93. [PMID: 9416598 PMCID: PMC2143619 DOI: 10.1002/pro.5560061201] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Mutans streptococci glucosyltransferases catalyze glucosyl transfer from sucrose to a glucan chain. We previously identified an aspartyl residue that participates in stabilizing the glucosyl transition state. The sequence surrounding the aspartate was found to have substantial sequence similarity with members of alpha-amylase family. Because little is known of the protein structure beyond the amino acid sequence, we used a knowledge-based interactive algorithm, MACAW, which provided significant level of homology with alpha-amylases and glucosyltransferase from Streptococcus downei gtfI (GTF). The significance of GTF similarity is underlined by GTF/alpha-amylase residues conserved in all but one alpha-amylase invariant residues. Site-directed mutagenesis of the three GTF catalytic residues are homologous with the alpha-amylase catalytic triad. The glucosyltransferases are members of the 4/7-superfamily that have a (beta/alpha)8-barrel structure and belong to family 13 of the glycohydralases.
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Affiliation(s)
- K S Devulapalle
- Department of Basic Sciences, School of Dentistry, University of Southern California, Los Angeles 90089-0641, USA
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21
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Brenner SE, Chothia C, Hubbard TJ. Population statistics of protein structures: lessons from structural classifications. Curr Opin Struct Biol 1997; 7:369-76. [PMID: 9204279 DOI: 10.1016/s0959-440x(97)80054-1] [Citation(s) in RCA: 128] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Structural classifications aid the interpretation of proteins by describing degrees of structural and evolutionary relatedness. They have also recently revealed strikingly skewed distributions at all levels; for example, a small number of folds are far more common than others, and just a few superfamilies are known to have diverged widely. The classifications also provide an indication of the total number of superfamilies in nature.
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Affiliation(s)
- S E Brenner
- Structural Biology Centre, National Institute for Bioscience and Human-Technology, Ibaraki, Japan.
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22
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Watanabe K, Hata Y, Kizaki H, Katsube Y, Suzuki Y. The refined crystal structure of Bacillus cereus oligo-1,6-glucosidase at 2.0 A resolution: structural characterization of proline-substitution sites for protein thermostabilization. J Mol Biol 1997; 269:142-53. [PMID: 9193006 DOI: 10.1006/jmbi.1997.1018] [Citation(s) in RCA: 194] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The crystal structure of oligo-1,6-glucosidase (dextrin 6-alpha-glucanohydrolase, EC 3.2.1.10) from Bacillus cereus ATCC7064 has been refined to 2.0 A resolution with an R-factor of 19.6% for 43,328 reflections. The final model contains 4646 protein atoms and 221 ordered water molecules with respective root-mean-square deviations of 0.015 A for bond lengths and of 3.166 degrees for bond angles from the ideal values. The structure consists of three domains: the N-terminal domain (residues 1 to 104 and 175 to 480), the subdomain (residues 105 to 174) and the C-terminal domain (residues 481 to 558). The N-terminal domain takes a (beta/alpha)8-barrel structure with additions of an alpha-helix (N alpha6') between the sixth strand Nbeta6 and the sixth helix N alpha6, an alpha-helix (N alpha7') between the seventh strand Nbeta7 and the seventh helix N alpha7 and three alpha-helices (N alpha8', N alpha8" and N alpha8'" between the eighth strand Nbeta8 and the eighth helix N alpha8. The subdomain is composed of an alpha-helix, a three-stranded antiparallel beta-sheet, and long intervening loops. The C-terminal domain has a beta-barrel structure of eight antiparallel beta-strands folded in double Greek key motifs, which is distorted in the sixth strand Cbeta6. Three catalytic residues, Asp199, Glu255 and Asp329, are located at the bottom of a deep cleft formed by the subdomain and a cluster of the two additional alpha-helices N alpha8' and N alpha8" in the (beta/alpha)8-barrel. The refined structure reveals the locations of 21 proline-substitution sites that are expected to be critical to protein thermostabilization from a sequence comparison among three Bacillus oligo-1,6-glucosidases with different thermostability. These sites lie in loops, beta-turns and alpha-helices, in order of frequency, except for Cys515 in the fourth beta-strand Cbeta4 of the C-terminal domain. The residues in beta-turns (Lys121, Glu208, Pro257, Glu290, Pro443, Lys457 and Glu487) are all found at their second positions, and those in alpha-helices (Asn109, Glu175, Thr261 and Ile403) are present at their N1 positions of the first helical turns. Those residues in both secondary structures adopt phi and phi values favorable for proline substitution. Residues preceding the 21 sites are mostly conserved upon proline occurrence at these 21 sites in more thermostable Bacillus oligo-1,6-glucosidases. These structural features with respect to the 21 sites indicate that the sites in beta-turns and alpha-helices have more essential prerequisites for proline substitution to thermostabilize the protein than those in loops. This well supports the previous finding that the replacement at the appropriate positions in beta-turns or alpha-helices is the most effective for protein thermostabilization by proline substitution.
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Affiliation(s)
- K Watanabe
- Department of Agricultural Chemistry, Kyoto Prefectural University, Shimogamo, Sakyo, Japan
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23
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Suzuki Y, Sugita N, Kishimoto T. Purification and Characterization of an Oligo-1,6-glucosidase from the Caldoactive ThermophileBacillus caldotenax. STARCH-STARKE 1997. [DOI: 10.1002/star.19970490406] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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24
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Watanabe K, Kitamura K, Suzuki Y. Analysis of the critical sites for protein thermostabilization by proline substitution in oligo-1,6-glucosidase from Bacillus coagulans ATCC 7050 and the evolutionary consideration of proline residues. Appl Environ Microbiol 1996; 62:2066-73. [PMID: 8787404 PMCID: PMC167984 DOI: 10.1128/aem.62.6.2066-2073.1996] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
To identify the critical sites for protein thermostabilization by proline substitution, the gene for oligo-1,6- glucosidase from a thermophilic Bacillus coagulans strain, ATCC 7050, was cloned as a 2.4-kb DNA fragment and sequenced. In spite of a big difference in their thermostabilities, B. coagulans oligo-1,6-glucosidase had a large number of points in its primary structure identical to respective points in the same enzymes from a mesophilic Bacillus cereus strain, ATCC 7064 (57%), and an obligately thermophilic Bacillus thermoglucosidasius strain, KP1006 (59%). The number of prolines (19 for B. cereus oligo-1,6-glucosidase, 24 for B. coagulans enzyme, and 32 for B. thermoglucosidasius enzyme) was observed to increase with the rise in thermostabilities of the oligo-1,6-glucosidases. Classification of proline residues in light of the amino acid sequence alignment and the protein structure revealed by X-ray crystallographic analysis also supported this tendency. Judging from proline residues occurring in B. coagulans oligo-1,6-glucosidase and the structural requirement for proline substitution (second site of the beta turn and first turn of the alpha helix) (K. Watanabe, T. Masuda, H. Ohashi, H. Mihara, and Y. Suzuki, Eur. J. Biochem. 226:277-283, 1994), the critical sites for thermostabilization were found to be Lys-121, Glu-290, Lys-457, and Glu-487 in B. cereus oligo-1,6-glucosidase. With regard to protein evolution, the oligo-1,6-glucosidases very likely follow the neutral theory. The adaptive mutations of the oligo-1,6-glucosidases that appear to increase thermostability are consistent with the substitution of proline residues for neutrally occurring residues. It is concluded that proline substitution is an important factor for the selection of thermostability in oligo-1,6-glucosidases.
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Affiliation(s)
- K Watanabe
- Department of Agricultural Chemistry, Kyoto Prefectural University, Japan
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25
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Janecek S. Invariant glycines and prolines flanking in loops the strand beta 2 of various (alpha/beta)8-barrel enzymes: a hidden homology? Protein Sci 1996; 5:1136-43. [PMID: 8762144 PMCID: PMC2143438 DOI: 10.1002/pro.5560050615] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The question of parallel (alpha/beta)8-barrel fold evolution remains unclear, owing mainly to the lack of sequence homology throughout the amino acid sequences of (alpha/beta)8-barrel enzymes. The "classical" approaches used in the search for homologies among (alpha/beta)8-barrels (e.g., production of structurally based alignments) have yielded alignments perfect from the structural point of view, but the approaches have been unable to reveal the homologies. These are proposed to be "hidden" in (alpha/beta)8-barrel enzymes. The term "hidden homology" means that the alignment of sequence stretches proposed to be homologous need not be structurally fully satisfactory. This is due to the very long evolutionary history of all (alpha/beta)8-barrels. This work identifies so-called hidden homology around the strand beta 2 that is flanked by loops containing invariant glycines and prolines in 17 different (alpha/beta)8-barrel enzymes, i.e., roughly in half of all currently known (alpha/beta)8-barrel proteins. The search was based on the idea that a conserved sequence region of an (alpha/beta)8-barrel enzyme should be more or less conserved also in the equivalent part of the structure of the other enzymes with this folding motif, given their mutual evolutionary relatedness. For this purpose, the sequence region around the well-conserved second beta-strand of alpha-amylase flanked by the invariant glycine and proline (56_GFTAIWITP, Aspergillus oryzae alpha-amylase numbering), was used as the sequence-structural template. The proposal that the second beta-strand of (alpha/beta)8-barrel fold is important from the evolutionary point of view is strongly supported by the increasing trend of the observed beta 2-strand structural similarity for the pairs of (alpha/beta)8-barrel enzymes: alpha-amylase and the alpha-subunit of tryptophan synthase, alpha-amylase and mandelate racemase, and alpha-amylase and cyclodextrin glycosyltransferase. This trend is also in agreement with the existing evolutionary division of the entire family of (alpha/beta)8-barrel proteins.
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Affiliation(s)
- S Janecek
- Institute of Ecobiology, Slovak Academy of Sciences, Bratislava, Slovakia.
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26
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MacGregor EA, Jespersen HM, Svensson B. A circularly permuted alpha-amylase-type alpha/beta-barrel structure in glucan-synthesizing glucosyltransferases. FEBS Lett 1996; 378:263-6. [PMID: 8557114 DOI: 10.1016/0014-5793(95)01428-4] [Citation(s) in RCA: 128] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
A motif of amino acid residues, located at the active site and specific beta-strands in alpha-amylases, is recognized in alpha-1,3- and alpha-1,6-glucan-synthesizing glucosyltransferases, leading to the conclusion that these enzymes contain an alpha/beta-barrel closely related to the (beta/alpha)8-fold of the alpha-amylase superfamily. The secondary structure elements of the transferase barrel, however, are circularly permuted to start with an alpha-helix equivalent to helix 3 in the alpha-amylases. Thus, the transferase counterpart of the long third beta-->alpha connection--constituting a domain in the alpha-amylases--is divided to precede and succeed the barrel. This architectural arrangement may be coupled to sucrose scission and glucosyl transfer. The involvement in the mechanism in glucosyltransferases of active site residues recurring in amylolytic enzymes is discussed.
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Affiliation(s)
- E A MacGregor
- Department of Chemistry, University of Manitoba, Winnipeg, Canada
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27
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Structure and activity of some starch-metabolising enzymes. ACTA ACUST UNITED AC 1996. [DOI: 10.1016/s0921-0423(96)80364-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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28
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Janecek S. Similarity of different beta-strands flanked in loops by glycines and prolines from distinct (alpha/beta)8-barrel enzymes: chance or a homology? Protein Sci 1995; 4:1239-42. [PMID: 7549888 PMCID: PMC2143142 DOI: 10.1002/pro.5560040622] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Many (alpha/beta)8-barrel enzymes contain their conserved sequence regions at or around the beta-strand segments that are often preceded and succeeded by glycines and prolines, respectively. alpha-Amylase is one of these enzymes. Its sequences exhibit a very low degree of similarity, but strong conservation is seen around its beta-strands. These conserved regions were used in the search for similarities with beta-strands of other (alpha/beta)8-barrel enzymes. The analysis revealed an interesting similarity between the segment around the beta 2-strand of alpha-amylase and the one around the beta 4-strand of glycolate oxidase that are flanked in loops by glycines and prolines. The similarity can be further extended on other members of the alpha-amylase and glycolate oxidase subfamilies, i.e., cyclodextrin glycosyltransferase and oligo-1,6-glucosidase, and flavocytochrome b2, respectively. Moreover, the alpha-subunit of tryptophan synthase, the (alpha/beta)8-barrel enzyme belonging to the other subfamily of (alpha/beta)8-barrels, has both investigated strands, beta 2 and beta 4, similar to beta 2 of alpha-amylase and beta 4 of glycolate oxidase. The possibilities of whether this similarity exists only by chance or is a consequence of some processes during the evolution of (alpha/beta)8-barrel proteins are briefly discussed.
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Affiliation(s)
- S Janecek
- Institute of Ecobiology, Slovak Academy of Sciences, Bratislava
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29
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Mutational analysis of catalytic mechanism and specificity in amylolytic enzymes. ACTA ACUST UNITED AC 1995. [DOI: 10.1016/s0921-0423(06)80099-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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30
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Schwermann B, Pfau K, Liliensiek B, Schleyer M, Fischer T, Bakker EP. Purification, properties and structural aspects of a thermoacidophilic alpha-amylase from Alicyclobacillus acidocaldarius atcc 27009. Insight into acidostability of proteins. EUROPEAN JOURNAL OF BIOCHEMISTRY 1994; 226:981-91. [PMID: 7813489 DOI: 10.1111/j.1432-1033.1994.00981.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The alpha-amylase from the thermoacidophilic eubacterium Alicyclobacillus (Bacillus) acidocaldarius strain ATCC 27009 was studied as an example of an acidophilic protein. The enzyme was purified from the culture fluid. On an SDS/polyacrylamide gel, the protein an apparent molecular mass of 160 kDa, which is approximately 15% higher than that predicted from the nucleotide sequence. The difference is due to the enzyme being a glycoprotein. Deglycosylation or synthesis of the enzyme in Escherichia coli gave a product with the mass expected for the mature protein. The amylase hydrolyzed starch at random and from the inside, and its main hydrolysis products were maltotriose and maltose. It also formed glucose from starch (by hydrolysing the intermediate product maltotetraose to glucose and maltotriose) and exhibited some pullulanase activity. the pH and temperature optima were pH3 and 75 degrees C, respectively, characterizing the enzyme as being thermoacidophilic. Alignment of the sequence of the enzyme with that of its closest neutrophilic relatives and with that of alpha-1,4 or alpha-1,6 glycosidic-bond hydrolyzing enzymes of known three-dimensional structure showed that the acidophilic alpha-amylase contains approximately 30% less charged residues than do its closest relatives, that these residues are replaced by neutral polar residues, and that hot spots for these exchanges are likely to be located at the surface of the protein. Literature data show that similar effects are observed in three other acidophilic proteins. It is proposed that these proteins have adapted to the acidic environment by reducing the density of both positive and negative charges at their surface, that this effect circumvents electrostatic repulsion of charged groups at low pH, and thereby contributes to the acidostability of these proteins.
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Affiliation(s)
- B Schwermann
- Abteilung Mikrobiologie, Universität Osnabrück, Germany
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31
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Watanabe K, Masuda T, Ohashi H, Mihara H, Suzuki Y. Multiple proline substitutions cumulatively thermostabilize Bacillus cereus ATCC7064 oligo-1,6-glucosidase. Irrefragable proof supporting the proline rule. EUROPEAN JOURNAL OF BIOCHEMISTRY 1994; 226:277-83. [PMID: 8001545 DOI: 10.1111/j.1432-1033.1994.tb20051.x] [Citation(s) in RCA: 142] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Nine residues of Bacillus cereus ATCC7064 oligo-1,6-glucosidase were replaced stepwise with proline residues. Of the nine residues, Lys121, Glu208 and Glu290 were at second sites of beta turns; Asn109, Glu175 and Thr261 were at N-caps of alpha helices; Glu216, Glu270 and Glu378 were in coils within loops. The replacements were carried out in the order, Lys121-->Pro, Glu175-->Pro, Glu290-->Pro, Glu208-->Pro, Glu270-->Pro, Glu378-->Pro, Thr261-->Pro, Glu216-->Pro and Asn109-->Pro. The resultant nine active mutant enzymes contained 1-9 more proline residues than B. cereus oligo-1,6-glucosidase. The thermostability of these mutants was additively enhanced with the increase in the number of proline residues introduced. The increase in the thermostability was most remarkable when proline residues were introduced at second sites of beta turns or at N-caps of alpha helices. The above results afforded irrefragable proof for the proline rule as an effective principle for increasing protein thermostability [Suzuki, Y., Oishi, K., Nakano, H. & Nagayama, T. (1987) Appl. Microbiol. Biotechnol. 26, 546-551].
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Affiliation(s)
- K Watanabe
- Department of Agricultural Chemistry, Kyoto Prefectural University, Japan
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32
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Janecek S. Parallel beta/alpha-barrels of alpha-amylase, cyclodextrin glycosyltransferase and oligo-1,6-glucosidase versus the barrel of beta-amylase: evolutionary distance is a reflection of unrelated sequences. FEBS Lett 1994; 353:119-23. [PMID: 7926034 DOI: 10.1016/0014-5793(94)01019-6] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The structures of functionally related beta/alpha-barrel starch hydrolases, alpha-amylase, beta-amylase, cyclodextrin glycosyltransferase and oligo-1,6-glucosidase, are discussed, their mutual sequence similarities being emphasized. Since these enzymes (except for beta-amylase) along with the predicted set of more than ten beta/alpha-barrels from the alpha-amylase enzyme superfamily fulfil the criteria characteristic of the products of divergent evolution, their unrooted distance tree is presented.
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Affiliation(s)
- S Janecek
- Institute of Ecobiology, Slovak Academy of Sciences, Bratislava
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33
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Svensson B. Protein engineering in the alpha-amylase family: catalytic mechanism, substrate specificity, and stability. PLANT MOLECULAR BIOLOGY 1994; 25:141-57. [PMID: 8018865 DOI: 10.1007/bf00023233] [Citation(s) in RCA: 301] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Most starch hydrolases and related enzymes belong to the alpha-amylase family which contains a characteristic catalytic (beta/alpha)8-barrel domain. Currently known primary structures that have sequence similarities represent 18 different specificities, including starch branching enzyme. Crystal structures have been reported in three of these enzyme classes: the alpha-amylases, the cyclodextrin glucanotransferases, and the oligo-1,6-glucosidases. Throughout the alpha-amylase family, only eight amino acid residues are invariant, seven at the active site and a glycine in a short turn. However, comparison of three-dimensional models with a multiple sequence alignment suggests that the diversity in specificity arises by variation in substrate binding at the beta-->alpha loops. Designed mutations thus have enhanced transferase activity and altered the oligosaccharide product patterns of alpha-amylases, changed the distribution of alpha-, beta- and gamma-cyclodextrin production by cyclodextrin glucanotransferases, and shifted the relative alpha-1,4:alpha-1,6 dual-bond specificity of neopullulanase. Barley alpha-amylase isozyme hybrids and Bacillus alpha-amylases demonstrate the impact of a small domain B protruding from the (beta/alpha)8-scaffold on the function and stability. Prospects for rational engineering in this family include important members of plant origin, such as alpha-amylase, starch branching and debranching enzymes, and amylomaltase.
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Affiliation(s)
- B Svensson
- Department of Chemistry, Carlsberg Laboratory, Copenhagen Valby, Denmark
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34
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Nakao M, Nakayama T, Kakudo A, Inohara M, Harada M, Omura F, Shibano Y. Structure and expression of a gene coding for thermostable alpha-glucosidase with a broad substrate specificity from Bacillus sp. SAM1606. EUROPEAN JOURNAL OF BIOCHEMISTRY 1994; 220:293-300. [PMID: 8125087 DOI: 10.1111/j.1432-1033.1994.tb18625.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
We cloned an alpha-glucosidase gene from thermophilic Bacillus sp. SAM1606 to overexpress it in Escherichia coli transformants. Deletion of the 5'-noncoding region as well as expression of the alpha-glucosidase gene under the control of the icp promotor of the insecticidal crystal protein gene from Bacillus thuringiensis subsp. sotto enhanced the enzyme productivity to 23.5 U/ml, which was 12,000-fold higher than that obtained by the strain SAM1606. The open reading frame corresponding to the alpha-glucosidase encoded 587 amino acid residues including a residue coded by the initiation codon TTG, and the molecular mass of the alpha-glucosidase from N-terminal serine was calculated to be 68,886 Da. Sequence analysis revealed that the SAM1606 alpha-glucosidase belonged to the alpha-amylase family. The SAM1606 alpha-glucosidase showed extremely high sequence identity (62-65%) to the Bacillus cereus and Bacillus thermoglucosidasius oligo-1,6-glucosidases, which were 72% identical to each other. Sequence identity in the suggested active site regions were essentially the same (80-82%) among these three enzymes. However, the substrate specificity of the SAM1606 alpha-glucosidase was significantly different from those of the oligo-1,6-glucosidases. The thermostability of these three alpha-glucosidases could be correlated with the increase in the number of proline residues, whose occurrence was predicted at beta turns and coils in the enzymes.
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Affiliation(s)
- M Nakao
- Institute for Biomedical Research, Suntory Ltd., Osaka, Japan
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