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Xiang C, Ao YF, Höhne M, Bornscheuer UT. Shifting the pH Optima of ( R)-Selective Transaminases by Protein Engineering. Int J Mol Sci 2022; 23:ijms232315347. [PMID: 36499674 PMCID: PMC9736275 DOI: 10.3390/ijms232315347] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Revised: 12/01/2022] [Accepted: 12/03/2022] [Indexed: 12/12/2022] Open
Abstract
Amine transaminases (ATAs) are powerful biocatalysts for the stereoselective synthesis of chiral amines. However, wild-type ATAs usually show pH optima at slightly alkaline values and exhibit low catalytic activity under physiological conditions. For efficient asymmetric synthesis ATAs are commonly used in combination with lactate dehydrogenase (LDH, optimal pH: 7.5) and glucose dehydrogenase (GDH, optimal pH: 7.75) to shift the equilibrium towards the synthesis of the target chiral amine and hence their pH optima should fit to each other. Based on a protein structure alignment, variants of (R)-selective transaminases were rationally designed, produced in E. coli, purified and subjected to biochemical characterization. This resulted in the discovery of the variant E49Q of the ATA from Aspergillus fumigatus, for which the pH optimum was successfully shifted from pH 8.5 to 7.5 and this variant furthermore had a two times higher specific activity than the wild-type protein at pH 7.5. A possible mechanism for this shift of the optimal pH is proposed. Asymmetric synthesis of (R)-1-phenylethylamine from acetophenone in combination with LDH and GDH confirmed that the variant E49Q shows superior performance at pH 7.5 compared to the wild-type enzyme.
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Affiliation(s)
- Chao Xiang
- Department of Biotechnology and Enzyme Catalysis, Institute of Biochemistry, University of Greifswald, 17487 Greifswald, Germany
| | - Yu-Fei Ao
- Department of Biotechnology and Enzyme Catalysis, Institute of Biochemistry, University of Greifswald, 17487 Greifswald, Germany
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Molecular Recognition and Function, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Matthias Höhne
- Department of Biotechnology and Enzyme Catalysis, Institute of Biochemistry, University of Greifswald, 17487 Greifswald, Germany
| | - Uwe T. Bornscheuer
- Department of Biotechnology and Enzyme Catalysis, Institute of Biochemistry, University of Greifswald, 17487 Greifswald, Germany
- Correspondence:
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Zhou Y, Ke F, Chen L, Lu Y, Zhu L, Chen X. Enhancing regioselectivity of sucrose phosphorylase by loop engineering for glycosylation of L-ascorbic acid. Appl Microbiol Biotechnol 2022; 106:4575-4586. [PMID: 35739344 DOI: 10.1007/s00253-022-12030-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 06/09/2022] [Accepted: 06/10/2022] [Indexed: 11/26/2022]
Abstract
Sucrose phosphorylase (SPase) has a remarkable capacity to synthesize numerous glucosides from abundantly available sucrose under mild conditions but suffers from specificity and regioselectivity issues. In this study, a loop engineering strategy was introduced to enhance the regioselectivity and substrate specificity of SPase for the efficient synthesis of 2-O-α-D-glucopyranosyl-L-ascorbic acid (AA-2G) via L-ascorbic acid (L-AA). P134, L341, and L343 were identified as "hotspots" for modulating the flexibility of loops, which significantly influenced the H-bonding network of L-AA in the active site, as well as the entrance of the substrate channel, thereby altering the regioselectivity and substrate specificity. Finally, the mutant L341V/L343F, with near-perfect control of the selectivity synthesis of the 2-OH group of L-AA (> 99%), was obtained. The AA-2G production by the mutant reached 244 g L-1 in a whole-cell biotransformation system, and the conversion rate of L-AA reached 64%, which is the highest level reported to date. Our work also provides a successful loop engineering case for modulating the regioselectivity and specificity of sucrose phosphorylase. KEY POINTS: • "Hotspots" were identified in the flexible loops of sucrose phosphorylase. • Mutants exhibited improved regioselectivity and specificity against L-ascorbic acid. • Synthesized AA-2G with high yield and regioselectivity by whole-cell of mutant.
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Affiliation(s)
- Yaoyao Zhou
- Institute of Fermentation Engineering, Zhejiang University of Technology, Hangzhou, 310014, China
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, 18 Chaowang Road, Hangzhou, 310014, China
| | - Feifei Ke
- Institute of Fermentation Engineering, Zhejiang University of Technology, Hangzhou, 310014, China
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, 18 Chaowang Road, Hangzhou, 310014, China
| | - Luyi Chen
- Institute of Fermentation Engineering, Zhejiang University of Technology, Hangzhou, 310014, China
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, 18 Chaowang Road, Hangzhou, 310014, China
| | - Yuele Lu
- Institute of Fermentation Engineering, Zhejiang University of Technology, Hangzhou, 310014, China
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, 18 Chaowang Road, Hangzhou, 310014, China
| | - Linjiang Zhu
- Institute of Fermentation Engineering, Zhejiang University of Technology, Hangzhou, 310014, China.
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, 18 Chaowang Road, Hangzhou, 310014, China.
| | - Xiaolong Chen
- Institute of Fermentation Engineering, Zhejiang University of Technology, Hangzhou, 310014, China
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, 18 Chaowang Road, Hangzhou, 310014, China
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Cytokine and Chemokine Responses in Invasive Aspergillosis Following Hematopoietic Stem Cell Transplantation: Past Evidence for Future Therapy of Aspergillosis. J Fungi (Basel) 2021; 7:jof7090753. [PMID: 34575791 PMCID: PMC8468228 DOI: 10.3390/jof7090753] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2021] [Revised: 09/08/2021] [Accepted: 09/10/2021] [Indexed: 02/04/2023] Open
Abstract
Invasive pulmonary aspergillosis is a frequent complication in immunocompromised individuals, and it continues to be an important cause of mortality in patients undergoing hematopoietic stem cell transplantation. In addition to antifungal therapy used for mycoses, immune-modulatory molecules such as cytokines and chemokines can modify the host immune response and exhibit a promising form of antimicrobial therapeutics to combat invasive fungal diseases. Cytokine and chemokine profiles may also be applied as biomarkers during fungal infections and clinical research has demonstrated different activation patterns of cytokines in invasive mycoses such as aspergillosis. In this review, we summarize different aspects of cytokines that have been described to date and provide possible future directions in research on invasive pulmonary aspergillosis following hematopoietic stem cell transplantation. These findings suggest that cytokines and chemokines may serve as useful biomarkers to improve diagnosis and monitoring of infection.
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Zhou S, Liu Z, Xie W, Yu Y, Ning C, Yuan M, Mou H. Improving catalytic efficiency and maximum activity at low pH of Aspergillus neoniger phytase using rational design. Int J Biol Macromol 2019; 131:1117-1124. [DOI: 10.1016/j.ijbiomac.2019.03.140] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2019] [Revised: 03/08/2019] [Accepted: 03/21/2019] [Indexed: 10/27/2022]
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Körfer G, Novoa C, Kern J, Balla E, Grütering C, Davari MD, Martinez R, Vojcic L, Schwaneberg U. Directed evolution of an acid Yersinia mollaretii phytase for broadened activity at neutral pH. Appl Microbiol Biotechnol 2018; 102:9607-9620. [DOI: 10.1007/s00253-018-9308-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Revised: 08/05/2018] [Accepted: 08/06/2018] [Indexed: 01/25/2023]
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Fu D, Huang H, Meng K, Wang Y, Luo H, Yang P, Yuan T, Yao B. Improvement of Yersinia frederiksenii phytase performance by a single amino acid substitution. Biotechnol Bioeng 2009; 103:857-64. [PMID: 19378262 DOI: 10.1002/bit.22315] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A new phytase (APPA) with optimum pH 2.5--substantially lower than that of most of microbial phytases (pH 4.5-6.0)--was cloned from Yersinia frederiksenii and heterologously expressed in Escherichia coli. Containing the highly conserved motifs typical of histidine acid phosphatases, APPA has the highest identity (84%) to the Yersinia intermedia phytase (optimal pH 4.5), a member of histidine acid phosphatase family. Based on sequence alignment and molecular modeling of APPA and related phytases, APPA has only one divergent residue, Ser51, in close proximity to the catalytic site. To understand the acidic adaptation of APPA, five mutants (S51A, S51T, S51D, S51K, and S51I) were constructed by site-directed mutagenesis, expressed in E. coli, purified, and characterized. Mutants S51T and S51I exhibited a shift in the optimal pH from 2.5 to 4.5 and 5.0, respectively, confirming the role of Ser51 in defining the optimal pH. Thus, a previously unrecognized factor other than electrostatics--presumably the side-chain structure near the active site--contributes to the optimal pH for APPA activity. Compared with wild-type APPA, mutant S51T showed higher specific activity, greater activity over pH 2.0-5.5, and increased thermal and acid stability. These properties make S51T a better candidate than the wild-type APPA for use in animal feed.
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Affiliation(s)
- Dawei Fu
- Key Laboratory for Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, P.R. China
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Weaver JD, Ullah AHJ, Sethumadhavan K, Mullaney EJ, Lei XG. Impact of assay conditions on activity estimate and kinetics comparison of Aspergillus niger PhyA and Escherichia coli AppA2 phytases. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2009; 57:5315-5320. [PMID: 19530713 DOI: 10.1021/jf900261n] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Aspergillus niger PhyA and Escherichia coli AppA2 are increasingly used in animal feed for phosphorus nutrition and environmental protection. The objective of this study was to determine the impacts of assay conditions on activity estimates of these two phytases and to compare their biochemical characteristics at a pH similar to the stomach environment. The activities of the unpurified AppA2 were more variable than those of PhyA with three commonly used phytase activity assays. The variations associated with AppA2 were accounted for by buffer, pH, and the inclusion of Triton X-100 and BSA by approximately one-third each. At the commonly observed stomach pH of 3.5, the purified AppA2 had a lower affinity to phytate (a higher K(m)), but greater V(max), k(cat), and k(cat)/K(m) than those of PhyA. In summary, differences between AppA2 and PhyA in responses to activity assay conditions and in inherent kinetic properties should be considered in interpreting their feeding efficacy.
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Affiliation(s)
- Jeremy D Weaver
- Department of Animal Science, Cornell University, Ithaca, New York 14853, USA
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Dao TH, Hoang KQ. Dephosphorylation and quantification of organic phosphorus in poultry litter by purified phytic-acid high affinity Aspergillus phosphohydrolases. CHEMOSPHERE 2008; 72:1782-1787. [PMID: 18555509 DOI: 10.1016/j.chemosphere.2008.04.048] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2008] [Revised: 04/12/2008] [Accepted: 04/14/2008] [Indexed: 05/26/2023]
Abstract
Extracellular phosphohydrolases mediate the dephosphorylation of phosphoesters and influence bioavailability and loss of agricultural P to the environment to pose risks of impairment of sensitive aquatic ecosystems. Induction and culture of five strains of Aspergillus were conducted to develop a source of high-affinity and robust phosphohydrolases for detecting environmental P and quantifying bioactive P pools in heterogeneous environmental specimens. Enzyme stability and activity against organic P in poultry litter were evaluated in 71 samples collected across poultry producing regions of Arkansas, Maryland, and Oklahoma of the US Differences existed in strains' adaptability to fermentation medium as they showed a wide range of phytate-degrading activity. Phosphohydrolases from Aspergillus ficuum had highest activity when the strain was cultured on a primarily chemical medium, compared to Aspergillus oryzae which preferred a wheat bran-based organic medium. Kinetics parameters of A. ficuum enzymes (K(m)=210 microM; V(max) of 407 nmol s(-1)) indicated phytic acid-degrading potential equivalent to that of commercial preparations. Purified A. ficuum phosphohydrolases effectively quantified litter bioactive P pools, showing that organic P occurred at an average of 54 (+/-14)% of total P, compared to inorganic phosphates, which averaged 41 (+/-12)%. Litter management and land application options must consider the high water-extractable and organic P concentrations and the biological availability of the organic enzyme-labile P pool. Robustness of A. ficuum enzymes and simplicity of the in situ ligand-based enzyme assay may thus increase routine assessment of litter bioactive P composition to sense for on-farm accumulation of such environmentally-sensitive P forms.
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Affiliation(s)
- Thanh H Dao
- USDA, ARS, Environmental Management and ByProducts Utilization Laboratory, BARC-East, Bldg. 306 Powder Mill Road, Beltsville, MD 20705, USA.
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