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Ngawiset S, Ismail A, Murakami S, Pongsawasdi P, Rungrotmongkol T, Krusong K. Identification of crucial amino acid residues involved in large ring cyclodextrin synthesis by amylomaltase from Corynebacterium glutamicum. Comput Struct Biotechnol J 2023; 21:899-909. [PMID: 36698977 PMCID: PMC9860158 DOI: 10.1016/j.csbj.2023.01.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 01/08/2023] [Accepted: 01/09/2023] [Indexed: 01/11/2023] Open
Abstract
Amylomaltase can be used to synthesize large ring cyclodextrins (LR-CDs), applied as drug solubilizer, gene delivery vehicle and protein aggregation suppressor. This study aims to determine the functional amino acid positions of Corynebacterium glutamicum amylomaltase (CgAM) involved in LR-CD synthesis by site-directed mutagenesis approach and molecular dynamic simulation. Mutants named Δ167, Y23A, P228Y, E231Y, A413F and G417F were constructed, purified, and characterized. The truncated CgAM, Δ167 exhibited no starch transglycosylation activity, indicating that the N-terminal domain of CgAM is necessary for enzyme activity. The P228Y, A413F and G417F produced larger LR-CDs from CD36-CD40 as compared to CD29 by WT. A413F and G417F mutants produced significantly low LR-CD yield compared to the WT. The A413F mutation affected all tested enzyme activities (starch tranglycosylation, disproportionation and cyclization), while the G417F mutation hindered the cyclization activity. P228Y mutation significantly lowered the k cat of disproportionation activity, while E231Y mutant exhibited much higher k cat and K m values for starch transglycosylation, compared to that of the WT. In addition, Y23A mutation affected the kinetic parameters of starch transglycosylation and cyclization. Molecular dynamic simulation further confirmed these mutations' impacts on the CgAM and LR-CD interactions. Identified functional amino acids for LR-CD synthesis may serve as a model for future modification to improve the properties and yield of LR-CDs.
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Affiliation(s)
- Sirikul Ngawiset
- Center of Excellence in Structural and Computational Biology, Department of Biochemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand
| | - Abbas Ismail
- Center of Excellence in Structural and Computational Biology, Department of Biochemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand
| | - Shuichiro Murakami
- Department of Agricultural Chemistry, School of Agriculture, Meiji University, Kawasaki-shi, Kanagawa 214–8571, Japan
| | - Piamsook Pongsawasdi
- Starch and Cyclodextrin Research Unit, Department of Biochemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand
| | - Thanyada Rungrotmongkol
- Center of Excellence in Structural and Computational Biology, Department of Biochemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand,Program in Bioinformatics and Computational Chemistry, Graduate School, Chulalongkorn University, Bangkok 10330, Thailand
| | - Kuakarun Krusong
- Center of Excellence in Structural and Computational Biology, Department of Biochemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand,Corresponding author.
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A putative novel starch-binding domain revealed by in silico analysis of the N-terminal domain in bacterial amylomaltases from the family GH77. 3 Biotech 2021; 11:229. [PMID: 33968573 DOI: 10.1007/s13205-021-02787-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Accepted: 04/09/2021] [Indexed: 10/21/2022] Open
Abstract
The family GH77 contains 4-α-glucanotransferase acting on α-1,4-glucans, known as amylomaltase in prokaryotes and disproportionating enzyme in plants. A group of bacterial GH77 members, represented by amylomaltases from Escherichia coli and Corynebacterium glutamicum, possesses an N-terminal extension that forms a distinct immunoglobulin-like fold domain, of which no function has been identified. Here, in silico analysis of 100 selected sequences of N-terminal domain homologues disclosed several well-conserved residues, among which Tyr108 (E. coli amylomaltase numbering) may be involved in α-glucan binding. These N-terminal domains, therefore, may represent a new type of starch-binding domain and define a new CBM family. This hypothesis is supported by docking of maltooligosaccharides to the N-terminal domain in amylomaltases, representing the four clusters of the phylogenetic tree. SUPPLEMENTARY INFORMATION The online version contains supplementary material available at 10.1007/s13205-021-02787-8.
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Zhoukun L, Wenwen Z, Lei Z, Yanxin W, Yajuan Z, Yan Q, Xue L, Yan H, Zhongli C. Gene Expression and Biochemical Characterization of a GH77 4‐α‐Glucanotransferase CcGtase FromCorallococcussp. EGB. STARCH-STARKE 2019. [DOI: 10.1002/star.201800254] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Li Zhoukun
- Key Laboratory of Agricultural Environmental MicrobiologyMinistry of AgricultureCollege of Life ScienceNanjing Agricultural UniversityNanjing 210095P. R. China
| | - Zheng Wenwen
- Key Laboratory of Agricultural Environmental MicrobiologyMinistry of AgricultureCollege of Life ScienceNanjing Agricultural UniversityNanjing 210095P. R. China
| | - Zhang Lei
- Key Laboratory of Agricultural Environmental MicrobiologyMinistry of AgricultureCollege of Life ScienceNanjing Agricultural UniversityNanjing 210095P. R. China
| | - Wang Yanxin
- Key Laboratory of Agricultural Environmental MicrobiologyMinistry of AgricultureCollege of Life ScienceNanjing Agricultural UniversityNanjing 210095P. R. China
| | - Zhang Yajuan
- Key Laboratory of Agricultural Environmental MicrobiologyMinistry of AgricultureCollege of Life ScienceNanjing Agricultural UniversityNanjing 210095P. R. China
| | - Qiao Yan
- Key Laboratory of Agricultural Environmental MicrobiologyMinistry of AgricultureCollege of Life ScienceNanjing Agricultural UniversityNanjing 210095P. R. China
| | - Luo Xue
- Key Laboratory of Agricultural Environmental MicrobiologyMinistry of AgricultureCollege of Life ScienceNanjing Agricultural UniversityNanjing 210095P. R. China
| | - Huang Yan
- Key Laboratory of Agricultural Environmental MicrobiologyMinistry of AgricultureCollege of Life ScienceNanjing Agricultural UniversityNanjing 210095P. R. China
| | - Cui Zhongli
- Key Laboratory of Agricultural Environmental MicrobiologyMinistry of AgricultureCollege of Life ScienceNanjing Agricultural UniversityNanjing 210095P. R. China
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Tumhom S, Krusong K, Kidokoro SI, Katoh E, Pongsawasdi P. Significance of H461 at subsite +1 in substrate binding and transglucosylation activity of amylomaltase from Corynebacterium glutamicum. Arch Biochem Biophys 2018; 652:3-8. [PMID: 29885290 DOI: 10.1016/j.abb.2018.06.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Revised: 05/28/2018] [Accepted: 06/05/2018] [Indexed: 10/14/2022]
Abstract
Amylomaltase (AM) catalyzes inter- and intra-molecular transglycosylation reactions of glucan to yield linear and cyclic oligosaccharide products. The functional roles of the conserved histidine at position 461 in the active site of AM from Corynebacterium glutamicum (CgAM) was investigated. H461 A/S/D/R/W were constructed, their catalytic properties were compared to the wild-type (WT). A significant decrease in transglucosylation activities was observed, especially in H461A mutant, while hydrolysis activity was barely affected. The transglucosylation factor of the H461A-CgAM was decreased by 8.6 folds. WT preferred maltotriose (G3) as substrate for disproportionation reaction, but all H461 mutants showed higher preference for maltose (G2). Using G3 substrate, kcat/Km values of H461 mutated CgAMs were 40-64 folds lower, while the Km values were twice higher than those of WT. All mutants could not produce large-ring cyclodextrin (LR-CD) product. The heat capacity profile indicated that WT had higher thermal stability than H461A. The X-ray structure of WT showed two H-bonds between H461 and heptasaccharide analog at subsite +1, while no such bonding was observed from the model structure of H461A. The importance of H461 on substrate binding with CgAM was evidenced. We are the first to mutate an active site histidine in AM to explore its function.
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Affiliation(s)
- Suthipapun Tumhom
- Starch and Cyclodextrin Research Unit, Department of Biochemistry, Faculty of Science, Chulalongkorn University, Bangkok, 10330, Thailand
| | - Kuakarun Krusong
- Starch and Cyclodextrin Research Unit, Department of Biochemistry, Faculty of Science, Chulalongkorn University, Bangkok, 10330, Thailand; Structural and Computational Biology Research Group, Department of Biochemistry, Faculty of Science, Chulalongkorn University, Bangkok, 10330, Thailand
| | - Shun-Ichi Kidokoro
- Department of Bioengineering, Nagaoka University of Technology, Nagaoka, Niigata, 940-2188, Japan
| | - Etsuko Katoh
- Structural Biology Research Unit, Advanced Analysis Center, National Agriculture and Food Research Organization, 3-1-3 Kannondai, Tsukuba, 305-8617, Ibaraki, Japan
| | - Piamsook Pongsawasdi
- Starch and Cyclodextrin Research Unit, Department of Biochemistry, Faculty of Science, Chulalongkorn University, Bangkok, 10330, Thailand.
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Tumhom S, Krusong K, Pongsawasdi P. Y418 in 410s loop is required for high transglucosylation activity and large-ring cyclodextrin production of amylomaltase from Corynebacterium glutamicum. Biochem Biophys Res Commun 2017; 488:516-521. [PMID: 28522291 DOI: 10.1016/j.bbrc.2017.05.078] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Accepted: 05/14/2017] [Indexed: 01/10/2023]
Abstract
Amylomaltase catalyzes α-1,4 glucosyl transfer reaction to yield linear or cyclic oligosaccharide products. The aim of this work is to investigate functional roles of 410s loop unique to amylomaltase from Corynebacterium glutamicum (CgAM). Site-directed mutagenesis of Y418, the residue at the loop tip, was performed. Y418A/S/D/R/W/F - CgAMs were characterized and compared to the wild-type (WT). A significant decrease in starch transglucosylation, disproportionation and cyclization activities was observed. Specificity for G3 substrate in disproportionation reaction was not changed; however, Y418F showed an increase in preference for longer oligosaccharides G5 to G7. The catalytic efficiency of Y418 mutated CgAMs, except for Y418F, was significantly lower (up to 8- and 12- fold for the W and R mutants, respectively) than that of WT. The change was in the kcat, not the Km values which were around 16-20 mM. The profile of large-ring cyclodextrin (LR-CD) product was different; the principal product of Y418A/D/S was shifted to the larger size (CD36-CD40) while that of the WT and Y418F peaked at CD29-CD33. The product yield was reduced especially in W and R mutants. Hence Y418 in 410s loop of CgAM not only contributes to transglucosylation activities but also controls the amount and size of LR-CD products through the proposed hydrophobic stacking interaction and the suitable distance of loop channel for substrate entering. This is the first report to show the effect of the loop tip residue on LR-CD product formation.
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Affiliation(s)
- Suthipapun Tumhom
- Starch and Cyclodextrin Research Unit, Department of Biochemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand
| | - Kuakarun Krusong
- Starch and Cyclodextrin Research Unit, Department of Biochemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand
| | - Piamsook Pongsawasdi
- Starch and Cyclodextrin Research Unit, Department of Biochemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand.
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Nimpiboon P, Krusong K, Kaulpiboon J, Kidokoro SI, Pongsawasdi P. Roles of N287 in catalysis and product formation of amylomaltase from Corynebacterium glutamicum. Biochem Biophys Res Commun 2016; 478:759-64. [PMID: 27507216 DOI: 10.1016/j.bbrc.2016.08.021] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Accepted: 08/03/2016] [Indexed: 02/02/2023]
Abstract
Amylomaltase catalyzes intermolecular and intramolecular transglucosylation reactions to form linear and cyclic oligosaccharides, respectively. The aim of this work is to investigate the structure-function relationship of amylomaltase from a mesophilic Corynebacterium glutamicum (CgAM). Site-directed mutagenesis was performed to substitute Tyr for Asn287 (N287Y) to determine its role in controlling amylomaltase activity and product formation. Expression of the wild-type (WT) and N287Y was achieved by cultivating recombinant cells in the medium containing lactose at 16 °C for 14 h. The purified mutated enzyme showed a significant decrease in all transglucosylation activities while hydrolysis activity was not changed. Optimum temperature and pH for disproportionation reaction were slightly changed upon mutation while those for cyclization reaction were not changed. Interestingly, N287Y showed a change in large-ring cyclodextrin (LR-CD) product profile in which the larger size was observed together with an increase in thermostability and substrate preference for G5 in addition to G3. The secondary structure of the mutated enzyme was slightly changed in related to the WT as evidenced from circular dichroism analysis. This work thus demonstrates that N287 is required for transglucosylation activities of CgAM. Having an aromatic residue in this position increased thermostability, changed product profile and substrate preference but demolished most enzyme activities.
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Affiliation(s)
- Pitchanan Nimpiboon
- Program in Biotechnology, Faculty of Science, Chulalongkorn University, Bangkok, 10330, Thailand; Starch and Cyclodextrin Research Unit, Department of Biochemistry, Faculty of Science, Chulalongkorn University, Phayathai Road, Bangkok, 10330, Thailand
| | - Kuakarun Krusong
- Starch and Cyclodextrin Research Unit, Department of Biochemistry, Faculty of Science, Chulalongkorn University, Phayathai Road, Bangkok, 10330, Thailand
| | - Jarunee Kaulpiboon
- Department of Pre-clinical Science (Biochemistry), Faculty of Medicine, Thammasat University, Pathumthani, 12120, Thailand
| | - Shun-Ichi Kidokoro
- Department of Bioengineering, Nagaoka University of Technology, Nagaoka, Niigata, 940-2188, Japan
| | - Piamsook Pongsawasdi
- Starch and Cyclodextrin Research Unit, Department of Biochemistry, Faculty of Science, Chulalongkorn University, Phayathai Road, Bangkok, 10330, Thailand.
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Joo S, Kim S, Seo H, Kim KJ. Crystal Structure of Amylomaltase from Corynebacterium glutamicum. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2016; 64:5662-5670. [PMID: 27366969 DOI: 10.1021/acs.jafc.6b02296] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Amylomaltase is an essential enzyme in maltose utilization and maltodextrin metabolism, and it has been industrially used for the production of cyclodextrin and modification of starch. We determined the crystal structure of amylomaltase from Corynebacterium glutamicum (CgAM) at a resolution of 1.7 Å. Although CgAM forms a dimer without NaCl, it exists as a monomer in physiological concentration of NaCl. CgAM is composed of N- and C-terminal domains, which can be further divided into two and four subdomains, respectively. It exhibits a unique structural feature at the functionally unknown N-domain and also shows two striking differences at the C-domain compared to other amylomaltases. These differences at extended edge of the substrate-binding site might affect substrate specificity for large cyclodextrin formation. The bis-tris methane and sulfate molecules bound at the substrate-binding site of our current structure mimic the binding of the hydroxyl groups of glucose bound at subsites -1 and -2, respectively.
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Affiliation(s)
- Seongjoon Joo
- Structural and Molecular Biology Laboratory, School of Life Sciences and Biotechnology, Kyungpook National University , Daehak-ro 80, Buk-ku, Daegu 702-701, Republic of Korea
| | - Sangwoo Kim
- Structural and Molecular Biology Laboratory, School of Life Sciences and Biotechnology, Kyungpook National University , Daehak-ro 80, Buk-ku, Daegu 702-701, Republic of Korea
- School of Nano-Bioscience and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST) , Ulsan, 689-798, Republic of Korea
| | - Hogyun Seo
- Structural and Molecular Biology Laboratory, School of Life Sciences and Biotechnology, Kyungpook National University , Daehak-ro 80, Buk-ku, Daegu 702-701, Republic of Korea
| | - Kyung-Jin Kim
- Structural and Molecular Biology Laboratory, School of Life Sciences and Biotechnology, Kyungpook National University , Daehak-ro 80, Buk-ku, Daegu 702-701, Republic of Korea
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Janeček Š, Gabriško M. Remarkable evolutionary relatedness among the enzymes and proteins from the α-amylase family. Cell Mol Life Sci 2016; 73:2707-25. [PMID: 27154042 PMCID: PMC11108405 DOI: 10.1007/s00018-016-2246-6] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Accepted: 04/22/2016] [Indexed: 12/17/2022]
Abstract
The α-amylase is a ubiquitous starch hydrolase catalyzing the cleavage of the α-1,4-glucosidic bonds in an endo-fashion. Various α-amylases originating from different taxonomic sources may differ from each other significantly in their exact substrate preference and product profile. Moreover, it also seems to be clear that at least two different amino acid sequences utilizing two different catalytic machineries have evolved to execute the same α-amylolytic specificity. The two have been classified in the Cabohydrate-Active enZyme database, the CAZy, in the glycoside hydrolase (GH) families GH13 and GH57. While the former and the larger α-amylase family GH13 evidently forms the clan GH-H with the families GH70 and GH77, the latter and the smaller α-amylase family GH57 has only been predicted to maybe define a future clan with the family GH119. Sequences and several tens of enzyme specificities found throughout all three kingdoms in many taxa provide an interesting material for evolutionarily oriented studies that have demonstrated remarkable observations. This review emphasizes just the three of them: (1) a close relatedness between the plant and archaeal α-amylases from the family GH13; (2) a common ancestry in the family GH13 of animal heavy chains of heteromeric amino acid transporter rBAT and 4F2 with the microbial α-glucosidases; and (3) the unique sequence features in the primary structures of amylomaltases from the genus Borrelia from the family GH77. Although the three examples cannot represent an exhaustive list of exceptional topics worth to be interested in, they may demonstrate the importance these enzymes possess in the overall scientific context.
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Affiliation(s)
- Štefan Janeček
- Laboratory of Protein Evolution, Institute of Molecular Biology, Slovak Academy of Sciences, Dúbravská cesta 21, 84551, Bratislava, Slovakia.
- Department of Biology, Faculty of Natural Sciences, University of SS. Cyril and Methodius in Trnava, Nám. J. Herdu 2, 91701, Trnava, Slovakia.
| | - Marek Gabriško
- Laboratory of Protein Evolution, Institute of Molecular Biology, Slovak Academy of Sciences, Dúbravská cesta 21, 84551, Bratislava, Slovakia
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Nimpiboon P, Kaulpiboon J, Krusong K, Nakamura S, Kidokoro SI, Pongsawasdi P. Mutagenesis for improvement of activity and thermostability of amylomaltase from Corynebacterium glutamicum. Int J Biol Macromol 2016; 86:820-8. [PMID: 26875536 DOI: 10.1016/j.ijbiomac.2016.02.022] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Revised: 02/05/2016] [Accepted: 02/08/2016] [Indexed: 11/25/2022]
Abstract
This work aims to improve thermostability of amylomaltase from a mesophilic Corynebacterium glutamicum (CgAM) by random and site-directed mutagenesis. From error prone PCR, a mutated CgAM with higher thermostability at 50 °C compared to the wild-type was selected and sequenced. The result showed that the mutant contains a single mutation of A406V. Site-directed mutagenesis was then performed to construct A406V and A406L. Both mutated CgAMs showed higher intermolecular transglucosylation activity with an upward shift in the optimum temperature and a slight increase in the optimum pH for disproportionation and cyclization reactions. Thermostability of both mutated CgAMs at 35-40 °C was significantly increased with a higher peak temperature from DSC spectra when compared to the wild-type. A406V had a greater effect on activity and thermostability than A406L. The catalytic efficiency values kcat/Km of A406V- and A406L-CgAMs were 2.9 and 1.4 times higher than that of the wild-type, respectively, mainly due to a significant increase in kcat. LR-CD product analysis demonstrated that A406V gave higher product yield, especially at longer incubation time and higher temperature, in comparison to the wild-type enzyme.
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Affiliation(s)
- Pitchanan Nimpiboon
- Program in Biotechnology, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand; Starch and Cyclodextrin Research Unit, Department of Biochemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand
| | - Jarunee Kaulpiboon
- Department of Pre-Clinical Science, Biochemistry, Faculty of Medicine, Thammasat University, Pathumthani 12120, Thailand
| | - Kuakarun Krusong
- Starch and Cyclodextrin Research Unit, Department of Biochemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand
| | - Shigeyoshi Nakamura
- Department of Bioengineering, Nagaoka University of Technology, Nagaoka, Niigata 940-2188, Japan
| | - Shun-ichi Kidokoro
- Department of Bioengineering, Nagaoka University of Technology, Nagaoka, Niigata 940-2188, Japan
| | - Piamsook Pongsawasdi
- Starch and Cyclodextrin Research Unit, Department of Biochemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand.
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Characterization of amylomaltase from Thermus filiformis and the increase in alkaline and thermo-stability by E27R substitution. Process Biochem 2015. [DOI: 10.1016/j.procbio.2015.08.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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In silico analysis of family GH77 with focus on amylomaltases from borreliae and disproportionating enzymes DPE2 from plants and bacteria. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2015; 1854:1260-8. [PMID: 26006747 DOI: 10.1016/j.bbapap.2015.05.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Revised: 05/14/2015] [Accepted: 05/17/2015] [Indexed: 11/21/2022]
Abstract
The CAZy glycoside hydrolase (GH) family GH77 is a monospecific family containing 4-α-glucanotransferases that if from prokaryotes are known as amylomaltases and if from plants including algae are known as disproportionating enzymes (DPE). The family GH77 is a member of the α-amylase clan GH-H. The main difference discriminating a GH77 4-α-glucanotransferase from the main GH13 α-amylase family members is the lack of domain C succeeding the catalytic (β/α)8-barrel. Of more than 2400 GH77 members, bacterial amylomaltases clearly dominate with more than 2300 sequences; the rest being approximately equally represented by Archaea and Eucarya. The main goal of the present study was to deliver a detailed bioinformatics study of family GH77 (416 collected sequences) focused on amylomaltases from borreliae (containing unique sequence substitutions in functionally important positions) and plant DPE2 representatives (possessing an insert of ~140 residues between catalytic nucleophile and proton donor). The in silico analysis reveals that within the genus of Borrelia a gradual evolutionary transition from typical bacterial Thermus-like amylomaltases may exist to family-GH77 amylomaltase versions that currently possess progressively mutated the most important and otherwise invariantly conserved positions. With regard to plant DPE2, a large group of bacterial amylomaltases represented by the amylomaltase from Escherichia coli with a longer N-terminus was identified as a probable intermediary connection between Thermus-like and DPE2-like (existing also among bacteria) family GH77 members. The presented results concerning both groups, i.e. amylomaltases from borreliae and plant DPE2 representatives (with their bacterial counterpart), may thus indicate the direction for future experimental studies.
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