1
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Tan X, Liu Y, Zang J, Zhang T, Zhao G. Hyperthermostability of prawn ferritin nanocage facilitates its application as a robust nanovehicle for nutraceuticals. Int J Biol Macromol 2021; 191:152-160. [PMID: 34547309 DOI: 10.1016/j.ijbiomac.2021.09.067] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 09/07/2021] [Accepted: 09/11/2021] [Indexed: 10/20/2022]
Abstract
The favorable physicochemical properties are essential for the application of protein-based nanovehicles in the field of biomaterials. Herein, we found that the thermal stability of Marsupenaeus japonicus ferritin (MjFer) (Tm = 109.1 ± 0.4 °C) is markedly higher than human H-chain ferritin (HuHF) (Tm = 87.7 ± 0.3 °C), although they share a high structural similarity. Multiple results indicated that the promoted thermal stability of MjFer is mainly derived from the salt bridges located at the C3 interface. Consequently, MjFer exhibits strong protective effects on encapsulated curcumin upon exposure at high temperatures. In contrast, most of the curcumin loaded HuHF composites precipitated rapidly under the same conditions. These findings elucidated the molecular mechanism of the hyperthermostability of MjFer and illustrated that MjFer could act as a robust insulation nanocarrier for bioactive compounds against various thermal treatments.
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Affiliation(s)
- Xiaoyi Tan
- College of Food Science & Nutritional Engineering, China Agricultural University, Beijing Key Laboratory of Functional Food from Plant Resources, Beijing 100083, China; Research Center of Food Colloids and Delivery of Functionality, China Agricultural University, Beijing 100083, China
| | - Yu Liu
- College of Food Science & Nutritional Engineering, China Agricultural University, Beijing Key Laboratory of Functional Food from Plant Resources, Beijing 100083, China
| | - Jiachen Zang
- College of Food Science & Nutritional Engineering, China Agricultural University, Beijing Key Laboratory of Functional Food from Plant Resources, Beijing 100083, China
| | - Tuo Zhang
- College of Food Science & Nutritional Engineering, China Agricultural University, Beijing Key Laboratory of Functional Food from Plant Resources, Beijing 100083, China; Research Center of Food Colloids and Delivery of Functionality, China Agricultural University, Beijing 100083, China.
| | - Guanghua Zhao
- College of Food Science & Nutritional Engineering, China Agricultural University, Beijing Key Laboratory of Functional Food from Plant Resources, Beijing 100083, China
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2
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Cao JR, Fan FF, Lv CJ, Wang HP, Li Y, Hu S, Zhao WR, Chen HB, Huang J, Mei LH. Improving the Thermostability and Activity of Transaminase From Aspergillus terreus by Charge-Charge Interaction. Front Chem 2021; 9:664156. [PMID: 33937200 PMCID: PMC8081293 DOI: 10.3389/fchem.2021.664156] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Accepted: 03/23/2021] [Indexed: 11/13/2022] Open
Abstract
Transaminases that promote the amination of ketones into amines are an emerging class of biocatalysts for preparing a series of drugs and their intermediates. One of the main limitations of (R)-selective amine transaminase from Aspergillus terreus (At-ATA) is its weak thermostability, with a half-life (t 1/2) of only 6.9 min at 40°C. To improve its thermostability, four important residue sites (E133, D224, E253, and E262) located on the surface of At-ATA were identified using the enzyme thermal stability system (ETSS). Subsequently, 13 mutants (E133A, E133H, E133K, E133R, E133Q, D224A, D224H, D224K, D224R, E253A, E253H, E253K, and E262A) were constructed by site-directed mutagenesis according to the principle of turning the residues into opposite charged ones. Among them, three substitutions, E133Q, D224K, and E253A, displayed higher thermal stability than the wild-type enzyme. Molecular dynamics simulations indicated that these three mutations limited the random vibration amplitude in the two α-helix regions of 130-135 and 148-158, thereby increasing the rigidity of the protein. Compared to the wild-type, the best mutant, D224K, showed improved thermostability with a 4.23-fold increase in t 1/2 at 40°C, and 6.08°C increase in T 50 10 . Exploring the three-dimensional structure of D224K at the atomic level, three strong hydrogen bonds were added to form a special "claw structure" of the α-helix 8, and the residues located at 151-156 also stabilized the α-helix 9 by interacting with each other alternately.
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Affiliation(s)
- Jia-Ren Cao
- School of Biological and Chemical Engineering, Zhejiang University of Science and Technology, Hangzhou, China
| | - Fang-Fang Fan
- School of Biological and Chemical Engineering, Zhejiang University of Science and Technology, Hangzhou, China
| | - Chang-Jiang Lv
- School of Biological and Chemical Engineering, Zhejiang University of Science and Technology, Hangzhou, China
| | - Hong-Peng Wang
- School of Biological and Chemical Engineering, Zhejiang University of Science and Technology, Hangzhou, China
| | - Ye Li
- School of Biological and Chemical Engineering, Zhejiang University of Science and Technology, Hangzhou, China
| | - Sheng Hu
- School of Biotechnology and Chemical Engineering, NingboTech University, Ningbo, China
| | - Wei-Rui Zhao
- School of Biotechnology and Chemical Engineering, NingboTech University, Ningbo, China
| | - Hai-Bin Chen
- Enzymaster (Ningbo) Bio-Engineering Co., Ltd., Ningbo, China
| | - Jun Huang
- School of Biological and Chemical Engineering, Zhejiang University of Science and Technology, Hangzhou, China
| | - Le-He Mei
- School of Biotechnology and Chemical Engineering, NingboTech University, Ningbo, China.,Jinhua Advanced Research Institute, Jinhua, China.,Department of Chemical and Biological Engineering, Zhejiang University, Hangzhou, China
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3
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Meng Q, Capra N, Palacio CM, Lanfranchi E, Otzen M, van Schie LZ, Rozeboom HJ, Thunnissen AMWH, Wijma HJ, Janssen DB. Robust ω-Transaminases by Computational Stabilization of the Subunit Interface. ACS Catal 2020; 10:2915-2928. [PMID: 32953233 PMCID: PMC7493286 DOI: 10.1021/acscatal.9b05223] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 01/31/2020] [Indexed: 12/25/2022]
Abstract
Transaminases are attractive catalysts for the production of enantiopure amines. However, the poor stability of these enzymes often limits their application in biocatalysis. Here, we used a framework for enzyme stability engineering by computational library design (FRESCO) to stabilize the homodimeric PLP fold type I ω-transaminase from Pseudomonas jessenii. A large number of surface-located point mutations and mutations predicted to stabilize the subunit interface were examined. Experimental screening revealed that 10 surface mutations out of 172 tested were indeed stabilizing (6% success), whereas testing 34 interface mutations gave 19 hits (56% success). Both the extent of stabilization and the spatial distribution of stabilizing mutations showed that the subunit interface was critical for stability. After mutations were combined, 2 very stable variants with 4 and 6 mutations were obtained, which in comparison to wild type (T m app = 62 °C) displayed T m app values of 80 and 85 °C, respectively. These two variants were also 5-fold more active at their optimum temperatures and tolerated high concentrations of isopropylamine and cosolvents. This allowed conversion of 100 mM acetophenone to (S)-1-phenylethylamine (>99% enantiomeric excess) with high yield (92%, in comparison to 24% with the wild-type transaminase). Crystal structures mostly confirmed the expected structural changes and revealed that the most stabilizing mutation, I154V, featured a rarely described stabilization mechanism: namely, removal of steric strain. The results show that computational interface redesign can be a rapid and powerful strategy for transaminase stabilization.
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Affiliation(s)
- Qinglong Meng
- Biotransformation and Biocatalysis, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Nikolas Capra
- Biotransformation and Biocatalysis, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Cyntia M. Palacio
- Biotransformation and Biocatalysis, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Elisa Lanfranchi
- Biotransformation and Biocatalysis, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Marleen Otzen
- Biotransformation and Biocatalysis, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Luc Z. van Schie
- Biotransformation and Biocatalysis, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Henriëtte J. Rozeboom
- Biotransformation and Biocatalysis, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Andy-Mark W. H. Thunnissen
- Biotransformation and Biocatalysis, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Hein J. Wijma
- Biotransformation and Biocatalysis, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Dick B. Janssen
- Biotransformation and Biocatalysis, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
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4
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Fang J. A critical review of five machine learning-based algorithms for predicting protein stability changes upon mutation. Brief Bioinform 2019; 21:1285-1292. [PMID: 31273374 DOI: 10.1093/bib/bbz071] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 05/14/2019] [Accepted: 05/16/2019] [Indexed: 01/02/2023] Open
Abstract
A number of machine learning (ML)-based algorithms have been proposed for predicting mutation-induced stability changes in proteins. In this critical review, we used hypothetical reverse mutations to evaluate the performance of five representative algorithms and found all of them suffer from the problem of overfitting. This approach is based on the fact that if a wild-type protein is more stable than a mutant protein, then the same mutant is less stable than the wild-type protein. We analyzed the underlying issues and suggest that the main causes of the overfitting problem include that the numbers of training cases were too small, and the features used in the models were not sufficiently informative for the task. We make recommendations on how to avoid overfitting in this important research area and improve the reliability and robustness of ML-based algorithms in general.
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Affiliation(s)
- Jianwen Fang
- Computational & Systems Biology Branch, Biometric Research Program, Division of Cancer Treatment and Diagnosis, National Cancer Institute, 9609 Medical Center Drive, Rockville, MD 20850, USA
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5
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Wang Q, Sun J, Liu Z, Huang W, Xue C, Mao X. Coimmobilization of β-Agarase and α-Neoagarobiose Hydrolase for Enhancing the Production of 3,6-Anhydro-l-galactose. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2018; 66:7087-7095. [PMID: 29893561 DOI: 10.1021/acs.jafc.8b01974] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Here we report a simple and efficient method to produce 3,6-anhydro-l-galactose (l-AHG) and agarotriose (AO3) in one step by a multienzyme system with the coimmobilized β-agarase AgWH50B and α-neoagarobiose hydrolase K134D. K134D was obtained by AgaWH117 mutagenesis and showed improved thermal stability when immobilized via covalent bonds on functionalized magnetic nanoparticles. The obtained multienzyme biocatalyst was characterized by Fourier transform infrared spectroscopy (FTIR). Compared with free agarases, the coimmobilized agarases exhibited a relatively higher agarose-to-l-AHG conversion efficiency. The yield of l-AHG obtained with the coimmobilized agarases was 40.6%, which was 6.5% higher than that obtained with free agarases. After eight cycles, the multienzyme biocatalyst still preserved 46.4% of the initial activity. To the best of our knowledge, this is the first report where two different agarases were coimmobilized. These results demonstrated the feasibility of the new method to fabricate a new multienzyme system onto magnetic nanoparticles via covalent bonds to produce l-AHG.
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Affiliation(s)
- Qidong Wang
- College of Food Science and Engineering , Ocean University of China , Qingdao 266003 , China
| | - Jianan Sun
- College of Food Science and Engineering , Ocean University of China , Qingdao 266003 , China
| | - Zhen Liu
- College of Food Science and Engineering , Ocean University of China , Qingdao 266003 , China
| | - Wencan Huang
- College of Food Science and Engineering , Ocean University of China , Qingdao 266003 , China
| | - Changhu Xue
- College of Food Science and Engineering , Ocean University of China , Qingdao 266003 , China
- Laboratory for Marine Drugs and Bioproducts , Qingdao National Laboratory for Marine Science and Technology , Qingdao 266237 , China
| | - Xiangzhao Mao
- College of Food Science and Engineering , Ocean University of China , Qingdao 266003 , China
- Laboratory for Marine Drugs and Bioproducts , Qingdao National Laboratory for Marine Science and Technology , Qingdao 266237 , China
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6
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Zhu Y, Liu H, Qiao C, Li L, Jiang Z, Xiao A, Ni H. Characterization of an arylsulfatase from a mutant library of Pseudoalteromonas carrageenovora arylsulfatase. Int J Biol Macromol 2016; 96:370-376. [PMID: 27940339 DOI: 10.1016/j.ijbiomac.2016.12.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Revised: 11/29/2016] [Accepted: 12/05/2016] [Indexed: 11/25/2022]
Abstract
A library of Pseudoalteromonas carrageenovora arylsulfatase mutants was constructed by introducing random mutagenesis using error-prone PCR. After screening, one mutant strain was obtained whose arylsulfatase had improved thermal stability. Protein sequence analysis revealed one amino acid substitution of H260L. The mutant arylsulfatase (named H260L) retained higher residual activity than wild-type enzyme (named WT) after incubation at 45, 50, 55 and 60°C for 60min. Thermal inactivation analysis showed that the half-life (t1/2) value at 55°C for H260L was 40.6min, while that of WT was 9.1min. When p-nitrophenyl sulfate was used as a substrate, the optimal reaction temperature and pH for the mutant enzyme were 55°C and pH 8.0, respectively. H260L was stable over the pH range of 6.0-9.0. Inhibition assay with EDTA indicated that metal ions play an important role during the catalytic process of the mutant enzyme. The desulfation ratio against agar of Gracilaria lemaneiformis was 82%.
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Affiliation(s)
- Yanbing Zhu
- College of Food and Biological Engineering, Jimei University, Xiamen 361021, China; Fujian Provincial Key Laboratory of Food Microbiology and Enzyme Engineering, Xiamen 361021, China; Research Center of Food Biotechnology of Xiamen City, Xiamen 361021, China; Key Laboratory of Systemic Utilization and In-depth Processing of Economic Seaweed, Xiamen Southern Ocean Technology Center of China, Xiamen 361021, China
| | - Han Liu
- College of Food and Biological Engineering, Jimei University, Xiamen 361021, China
| | - Chaochao Qiao
- College of Food and Biological Engineering, Jimei University, Xiamen 361021, China
| | - Lijun Li
- College of Food and Biological Engineering, Jimei University, Xiamen 361021, China; Fujian Provincial Key Laboratory of Food Microbiology and Enzyme Engineering, Xiamen 361021, China; Research Center of Food Biotechnology of Xiamen City, Xiamen 361021, China; Key Laboratory of Systemic Utilization and In-depth Processing of Economic Seaweed, Xiamen Southern Ocean Technology Center of China, Xiamen 361021, China
| | - Zedong Jiang
- College of Food and Biological Engineering, Jimei University, Xiamen 361021, China; Fujian Provincial Key Laboratory of Food Microbiology and Enzyme Engineering, Xiamen 361021, China; Research Center of Food Biotechnology of Xiamen City, Xiamen 361021, China; Key Laboratory of Systemic Utilization and In-depth Processing of Economic Seaweed, Xiamen Southern Ocean Technology Center of China, Xiamen 361021, China
| | - Anfeng Xiao
- College of Food and Biological Engineering, Jimei University, Xiamen 361021, China; Fujian Provincial Key Laboratory of Food Microbiology and Enzyme Engineering, Xiamen 361021, China; Research Center of Food Biotechnology of Xiamen City, Xiamen 361021, China; Key Laboratory of Systemic Utilization and In-depth Processing of Economic Seaweed, Xiamen Southern Ocean Technology Center of China, Xiamen 361021, China
| | - Hui Ni
- College of Food and Biological Engineering, Jimei University, Xiamen 361021, China; Fujian Provincial Key Laboratory of Food Microbiology and Enzyme Engineering, Xiamen 361021, China; Research Center of Food Biotechnology of Xiamen City, Xiamen 361021, China; Key Laboratory of Systemic Utilization and In-depth Processing of Economic Seaweed, Xiamen Southern Ocean Technology Center of China, Xiamen 361021, China.
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7
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Ryu J, Kim H, Park HH, Lee HJ, Park JH, Rhee WJ, Park TH. Protein-stabilizing and cell-penetrating properties of α-helix domain of 30Kc19 protein. Biotechnol J 2016; 11:1443-1451. [PMID: 27440394 PMCID: PMC5132017 DOI: 10.1002/biot.201600040] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Revised: 07/06/2016] [Accepted: 07/07/2016] [Indexed: 11/09/2022]
Abstract
The protein-stabilizing and cell-penetrating activities of Bombyx mori 30Kc19 α-helix domain (30Kc19α) are investigated. Recently, 30Kc19 protein has been studied extensively as it has both protein-stabilizing and cell-penetrating properties. However, it is unknown which part of 30Kc19 is responsible for those properties. 30Kc19 protein is composed of two distinct domains, an α-helix N-terminal domain (30Kc19α) and a β-trefoil C-terminal domain (30Kc19β). The authors construct and produce truncated forms of 30Kc19 to demonstrate their biological functions. Interestingly, 30Kc19α was shown to be responsible for both the protein-stabilizing and cell-penetrating properties of 30Kc19 protein. 30Kc19α shows even higher protein delivery activity than did whole 30Kc19 protein and has low cytotoxicity when added to cell culture medium. Therefore, based on its multifunctional properties, 30Kc19α can be developed as a novel candidate for a therapeutic protein carrier into various cells and tissues.
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Affiliation(s)
- Jina Ryu
- Interdisciplinary Program for Bioengineering, Seoul National University, Seoul, Republic of Korea
| | - Hyoju Kim
- Interdisciplinary Program for Bioengineering, Seoul National University, Seoul, Republic of Korea
| | - Hee Ho Park
- The School of Chemical and Biological Engineering, Seoul National University, Seoul, Republic of Korea
| | - Hong Jai Lee
- The School of Chemical and Biological Engineering, Seoul National University, Seoul, Republic of Korea
| | - Ju Hyun Park
- Department of Medical Biomaterials Engineering, Kangwon National University, Chuncheon, Republic of Korea
| | - Won Jong Rhee
- Division of Bioengineering, Incheon National University, Incheon, Republic of Korea
| | - Tai Hyun Park
- Interdisciplinary Program for Bioengineering, Seoul National University, Seoul, Republic of Korea.,The School of Chemical and Biological Engineering, Seoul National University, Seoul, Republic of Korea.,Advanced Institutes of Convergence Technology, Suwon, Republic of Korea
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8
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Adding an appropriate amino acid during crosslinking results in more stable crosslinked enzyme aggregates. Anal Biochem 2016; 507:27-32. [PMID: 27237371 DOI: 10.1016/j.ab.2016.05.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Revised: 05/08/2016] [Accepted: 05/16/2016] [Indexed: 12/14/2022]
Abstract
Carrier free immobilization, especially crosslinked enzyme aggregates (CLEAs), has become an important design for biocatalysis in several areas. Adding amino acids during formation of CLEAs was found to give biocatalysts more stable at 55 °C and in the presence of 60% acetonitrile. The half-lives of CLEAs prepared with and without Arg addition were 21 and 15 h (subtilisin) and 4 and 1.6 h (α-chymotrypsin) at 55 °C, respectively. The corresponding half-lives during acetonitrile presence were 4.1 and 3.0 h (subtilisin) and 39 and 22 min (α-chymotrypsin), respectively. CLEAs made with Arg had higher percentages of alpha helix. CLEAs made by adding Lys, Ala, or Asp also were more stable. In the case of Thermomyces lanuginosus lipase (TLL), CLEA with Ala was even more stable than CLEA with Arg. The addition of a suitable amino acid, thus, enhances CLEA stabilities. The results are discussed in the light of earlier results on chemical modification of proteins and the observation that the Arg/Lys ratio is invariably high in the case of enzymes from thermophiles.
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9
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Su JG, Han XM, Zhao SX, Hou YX, Li XY, Qi LS, Wang JH. Impacts of the charged residues mutation S48E/N62H on the thermostability and unfolding behavior of cold shock protein: insights from molecular dynamics simulation with Gō model. J Mol Model 2016; 22:91. [DOI: 10.1007/s00894-016-2958-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Accepted: 03/07/2016] [Indexed: 10/22/2022]
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10
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Chen A, Li Y, Nie J, McNeil B, Jeffrey L, Yang Y, Bai Z. Protein engineering of Bacillus acidopullulyticus pullulanase for enhanced thermostability using in silico data driven rational design methods. Enzyme Microb Technol 2015. [DOI: 10.1016/j.enzmictec.2015.06.013] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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11
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Petrauskas V, Maximowitsch E, Matulis D. Thermodynamics of Ion Pair Formations Between Charged Poly(Amino Acid)s. J Phys Chem B 2015; 119:12164-71. [PMID: 26317887 DOI: 10.1021/acs.jpcb.5b05767] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Electrostatic interactions between the positively and negatively charged amino acids in proteins play an important role in macromolecular stability, binding, and recognition. Numerous amino acids in proteins are ionizable and may exist in negatively (e.g., Glu, Asp, Cys, Tyr) or positively (e.g., Arg, Lys, His, Orn) charged form dependent on pH and their pKas. In this work, isothermal titration calorimetry was used to determine the average standard values of thermodynamic parameters (the Gibbs free energy, enthalpy, entropy, and the heat capacity) of interaction between the positively charged amino acid homopolymers (polyarginine, polylysine, and polyornithine) and the negatively charged homopolymers (polyaspartic and polyglutamic acids). These values are of potential use in the computational models of interacting proteins and other biological macromolecules. The study showed that oppositely charged poly(amino acid)s bound each other with the stoichiometry of one positive to one negative charge. Arginine bound to the negatively charged amino acids with exothermic enthalpy and higher affinity than lysine. This result also suggests that positive charges in proteins should not be considered entirely equivalent if carried by lysine or arginine. The difference in binding energy of arginine and lysine association with the negatively charged amino acids was attributed to the enthalpy of the second ionic hydrogen bond formation between the guanidine and carboxylic groups. Despite the favorable enthalpic contribution, all such ion pair formation reactions were largely entropy-driven. Consistent with previously observed ionic interactions, the positive heat capacity was always observed during the amino acid ion pair formation.
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Affiliation(s)
- Vytautas Petrauskas
- Department of Biothermodynamics and Drug Design, Institute of Biotechnology, Vilnius University , V. A. Graičiu̅no 8, LT-02241 Vilnius, Lithuania
| | - Eglė Maximowitsch
- Department of Biothermodynamics and Drug Design, Institute of Biotechnology, Vilnius University , V. A. Graičiu̅no 8, LT-02241 Vilnius, Lithuania
| | - Daumantas Matulis
- Department of Biothermodynamics and Drug Design, Institute of Biotechnology, Vilnius University , V. A. Graičiu̅no 8, LT-02241 Vilnius, Lithuania
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12
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Pey AL, Majtan T, Kraus JP. The role of surface electrostatics on the stability, function and regulation of human cystathionine β-synthase, a complex multidomain and oligomeric protein. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2014; 1844:1453-62. [PMID: 24780582 DOI: 10.1016/j.bbapap.2014.04.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Revised: 04/06/2014] [Accepted: 04/21/2014] [Indexed: 11/25/2022]
Abstract
Human cystathionine β-synthase (hCBS) is a key enzyme of sulfur amino acid metabolism, controlling the commitment of homocysteine to the transsulfuration pathway and antioxidant defense. Mutations in hCBS cause inherited homocystinuria (HCU), a rare inborn error of metabolism characterized by accumulation of toxic homocysteine in blood and urine. hCBS is a complex multidomain and oligomeric protein whose activity and stability are independently regulated by the binding of S-adenosyl-methionine (SAM) to two different types of sites at its C-terminal regulatory domain. Here we study the role of surface electrostatics on the complex regulation and stability of hCBS using biophysical and biochemical procedures. We show that the kinetic stability of the catalytic and regulatory domains is significantly affected by the modulation of surface electrostatics through noticeable structural and energetic changes along their denaturation pathways. We also show that surface electrostatics strongly affect SAM binding properties to those sites responsible for either enzyme activation or kinetic stabilization. Our results provide new insight into the regulation of hCBS activity and stability in vivo with implications for understanding HCU as a conformational disease. We also lend experimental support to the role of electrostatic interactions in the recently proposed binding modes of SAM leading to hCBS activation and kinetic stabilization.
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Affiliation(s)
- Angel L Pey
- Department of Physical Chemistry, Faculty of Sciences, University of Granada, Av. Fuentenueva s/n, 18071 Granada, Spain.
| | - Tomas Majtan
- Department of Pediatrics, University of Colorado, School of Medicine, Aurora, CO 80045, USA
| | - Jan P Kraus
- Department of Pediatrics, University of Colorado, School of Medicine, Aurora, CO 80045, USA
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13
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Tan NY, Bailey UM, Jamaluddin MF, Mahmud SHB, Raman SC, Schulz BL. Sequence-based protein stabilization in the absence of glycosylation. Nat Commun 2014; 5:3099. [DOI: 10.1038/ncomms4099] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Accepted: 12/12/2013] [Indexed: 12/12/2022] Open
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14
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Zhang L, Tang X, Cui D, Yao Z, Gao B, Jiang S, Yin B, Yuan YA, Wei D. A method to rationally increase protein stability based on the charge-charge interaction, with application to lipase LipK107. Protein Sci 2013; 23:110-6. [PMID: 24353171 DOI: 10.1002/pro.2388] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Revised: 10/14/2013] [Accepted: 10/21/2013] [Indexed: 11/10/2022]
Abstract
We report a suite of enzyme redesign protocol based on the surface charge-charge interaction calculation, which is potentially applied to improve the stability of an enzyme without compromising its catalytic activity. Together with the experimental validation, we have released a suite of enzyme redesign algorithm Enzyme Thermal Stability System, written based on our model, for open access to meet the needs in wet labs. Lipk107, a lipase of a versatile industrial use, was chosen to test our software. Our calculation determined that four residues, D113, D149, D213, and D253, located on the surface of LipK107 were critical to the stability of the enzyme. The model was validated with mutagenesis at these four residues followed by stability and activity tests. LipK107 mutants D113A and D149K were more resistant to thermal inactivation with ∼10°C higher half-inactivation temperature than wild-type LipK107. Moreover, mutant D149K exhibited significant retention in residual activity under constant heat, showing a 14-fold increase in the half-inactivation time at 50°C. Activity tests showed that these mutants retained the equal or higher specific activity, among which noteworthy was the mutant D253A with as much as 20% higher activity. We suggest that our protocol could be used as a general guideline to redesign protein enzymes with increased stabilities and enhanced activities.
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Affiliation(s)
- Lujia Zhang
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, 200237, People's Republic of China; State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing University of Technology, Nanjing, Jiangsu 211800, People's Republic of China
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15
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Yu H, Huang H. Engineering proteins for thermostability through rigidifying flexible sites. Biotechnol Adv 2013; 32:308-15. [PMID: 24211474 DOI: 10.1016/j.biotechadv.2013.10.012] [Citation(s) in RCA: 172] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2013] [Revised: 09/04/2013] [Accepted: 10/29/2013] [Indexed: 01/06/2023]
Abstract
Engineering proteins for thermostability is an exciting and challenging field since it is critical for broadening the industrial use of recombinant proteins. Thermostability of proteins arises from the simultaneous effect of several forces such as hydrophobic interactions, disulfide bonds, salt bridges and hydrogen bonds. All of these interactions lead to decreased flexibility of polypeptide chain. Structural studies of mesophilic and thermophilic proteins showed that the latter need more rigid structures to compensate for increased thermal fluctuations. Hence flexibility can be an indicator to pinpoint weak spots for enhancing thermostability of enzymes. A strategy has been proven effective in enhancing proteins' thermostability with two steps: predict flexible sites of proteins firstly and then rigidify these sites. We refer to this approach as rigidify flexible sites (RFS) and give an overview of such a method through summarizing the methods to predict flexibility of a protein, the methods to rigidify residues with high flexibility and successful cases regarding enhancing thermostability of proteins using RFS.
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Affiliation(s)
- Haoran Yu
- Department of Biochemical Engineering, School of Chemical Engineering and Technology, Key Laboratory of Systems Bioengineering, Ministry of Education, Tianjin University, Tianjin 300072, China
| | - He Huang
- Department of Biochemical Engineering, School of Chemical Engineering and Technology, Key Laboratory of Systems Bioengineering, Ministry of Education, Tianjin University, Tianjin 300072, China.
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16
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Yennamalli RM, Rader AJ, Kenny AJ, Wolt JD, Sen TZ. Endoglucanases: insights into thermostability for biofuel applications. BIOTECHNOLOGY FOR BIOFUELS 2013; 6:136. [PMID: 24070146 PMCID: PMC3856469 DOI: 10.1186/1754-6834-6-136] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2013] [Accepted: 09/24/2013] [Indexed: 05/03/2023]
Abstract
Obtaining bioethanol from cellulosic biomass involves numerous steps, among which the enzymatic conversion of the polymer to individual sugar units has been a main focus of the biotechnology industry. Among the cellulases that break down the polymeric cellulose are endoglucanases that act synergistically for subsequent hydrolytic reactions. The endoglucanases that have garnered relatively more attention are those that can withstand high temperatures, i.e., are thermostable. Although our understanding of thermostability in endoglucanases is incomplete, some molecular features that are responsible for increased thermostability have been recently identified. This review focuses on the investigations of endoglucanases and their implications for biofuel applications.
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Affiliation(s)
- Ragothaman M Yennamalli
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames 50011, IA, USA
- Present Address: Department of Biochemistry and Cell Biology, Rice University, Houston, TX 77005, USA
| | - Andrew J Rader
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis 46202, IN, USA
- Present Address: State Farm Insurance, Indianapolis 46240, IN, USA
| | - Adam J Kenny
- Biosafety Institute for Genetically Modified Agricultural Products and Department of Agronomy, Iowa State University, Ames 50011, IA, USA
- Present Address: Brownells, Inc, Montezuma, IA 50171, USA
| | - Jeffrey D Wolt
- Biosafety Institute for Genetically Modified Agricultural Products and Department of Agronomy, Iowa State University, Ames 50011, IA, USA
| | - Taner Z Sen
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames 50011, IA, USA
- Bioinformatics and Computational Biology Program, Iowa State University, Ames 50011, IA, USA
- 1025 Crop Genome Informatics Lab, Iowa State University, Ames 50011, IA, USA
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17
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Tadokoro T, Kazama H, Koga Y, Takano K, Kanaya S. Investigating the Structural Dependence of Protein Stabilization by Amino Acid Substitution. Biochemistry 2013; 52:2839-47. [DOI: 10.1021/bi400076f] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Takashi Tadokoro
- Department of Material and Life
Science, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Hirotaka Kazama
- Department of Material and Life
Science, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Yuichi Koga
- Department of Material and Life
Science, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Kazufumi Takano
- Department of Material and Life
Science, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
- Department of Biomolecular Chemistry, Kyoto Prefectural University, 1-5 Hangi-cho, Shimogamo,
Sakyo-ku, Kyoto 606-8522, Japan
| | - Shigenori Kanaya
- Department of Material and Life
Science, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
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18
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Li Y, Fang J. PROTS-RF: a robust model for predicting mutation-induced protein stability changes. PLoS One 2012; 7:e47247. [PMID: 23077576 PMCID: PMC3471942 DOI: 10.1371/journal.pone.0047247] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Accepted: 09/11/2012] [Indexed: 11/19/2022] Open
Abstract
The ability to improve protein thermostability via protein engineering is of great scientific interest and also has significant practical value. In this report we present PROTS-RF, a robust model based on the Random Forest algorithm capable of predicting thermostability changes induced by not only single-, but also double- or multiple-point mutations. The model is built using 41 features including evolutionary information, secondary structure, solvent accessibility and a set of fragment-based features. It achieves accuracies of 0.799,0.782, 0.787, and areas under receiver operating characteristic (ROC) curves of 0.873, 0.868 and 0.862 for single-, double- and multiple- point mutation datasets, respectively. Contrary to previous suggestions, our results clearly demonstrate that a robust predictive model trained for predicting single point mutation induced thermostability changes can be capable of predicting double and multiple point mutations. It also shows high levels of robustness in the tests using hypothetical reverse mutations. We demonstrate that testing datasets created based on physical principles can be highly useful for testing the robustness of predictive models.
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Affiliation(s)
- Yunqi Li
- Applied Bioinformatics Laboratory, The University of Kansas, Lawrence, Kansas, United States of America
| | - Jianwen Fang
- Applied Bioinformatics Laboratory, The University of Kansas, Lawrence, Kansas, United States of America
- * E-mail:
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19
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Fang Y, Middaugh CR, Fang J. In silico classification of proteins from acidic and neutral cytoplasms. PLoS One 2012; 7:e45585. [PMID: 23049817 PMCID: PMC3458925 DOI: 10.1371/journal.pone.0045585] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2012] [Accepted: 08/23/2012] [Indexed: 01/05/2023] Open
Abstract
Protein acidostability is a common problem in biopharmaceutical and other industries. However, it remains a great challenge to engineer proteins for enhanced acidostability because our knowledge of protein acidostabilization is still very limited. In this paper, we present a comparative study of proteins from bacteria with acidic (AP) and neutral cytoplasms (NP) using an integrated statistical and machine learning approach. We construct a set of 393 non-redundant AP-NP ortholog pairs and calculate a total of 889 sequence based features for these proteins. The pairwise alignments of these ortholog pairs are used to build a residue substitution propensity matrix between APs and NPs. We use Gini importance provided by the Random Forest algorithm to rank the relative importance of these features. A scoring function using the 10 most significant features is developed and optimized using a hill climbing algorithm. The accuracy of the score function is 86.01% in predicting AP-NP ortholog pairs and is 76.65% in predicting non-ortholog AP-NP pairs, suggesting that there are significant differences between APs and NPs which can be used to predict relative acidostability of proteins. The overall trends uncovered in the study can be used as general guidelines for designing acidostable proteins. To best of our knowledge, this work represents the first systematic comparative study of the acidostable proteins and their non-acidostable orthologs.
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Affiliation(s)
- Yaping Fang
- Applied Bioinformatics Laboratory, The University of Kansas, Lawrence, Kansas, United States of America
| | - C. Russell Middaugh
- Department of Pharmaceutical Chemistry, The University of Kansas, Lawrence, Kansas, United States of America
| | - Jianwen Fang
- Applied Bioinformatics Laboratory, The University of Kansas, Lawrence, Kansas, United States of America
- * E-mail:
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20
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Murphy GS, Mills JL, Miley MJ, Machius M, Szyperski T, Kuhlman B. Increasing sequence diversity with flexible backbone protein design: the complete redesign of a protein hydrophobic core. Structure 2012; 20:1086-96. [PMID: 22632833 PMCID: PMC3372604 DOI: 10.1016/j.str.2012.03.026] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2011] [Revised: 02/15/2012] [Accepted: 03/30/2012] [Indexed: 01/07/2023]
Abstract
Protein design tests our understanding of protein stability and structure. Successful design methods should allow the exploration of sequence space not found in nature. However, when redesigning naturally occurring protein structures, most fixed backbone design algorithms return amino acid sequences that share strong sequence identity with wild-type sequences, especially in the protein core. This behavior places a restriction on functional space that can be explored and is not consistent with observations from nature, where sequences of low identity have similar structures. Here, we allow backbone flexibility during design to mutate every position in the core (38 residues) of a four-helix bundle protein. Only small perturbations to the backbone, 1-2 Å, were needed to entirely mutate the core. The redesigned protein, DRNN, is exceptionally stable (melting point >140°C). An NMR and X-ray crystal structure show that the side chains and backbone were accurately modeled (all-atom RMSD = 1.3 Å).
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Affiliation(s)
- Grant S. Murphy
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599-3290, USA
| | - Jeffrey L. Mills
- Department of Chemistry, State University of New York at Buffalo, Buffalo, NY, 14260, USA
,Northeast Structural Genomics Consortium
| | - Michael J. Miley
- Center for Structural Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Mischa Machius
- Center for Structural Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Thomas Szyperski
- Department of Chemistry, State University of New York at Buffalo, Buffalo, NY, 14260, USA
,Northeast Structural Genomics Consortium
| | - Brian Kuhlman
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599-7260, USA
,Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
,corresponding author. , Phone: 919-843-0188, Fax: 919-966-2852
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21
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Electrostatic contribution of surface charge residues to the stability of a thermophilic protein: benchmarking experimental and predicted pKa values. PLoS One 2012; 7:e30296. [PMID: 22279578 PMCID: PMC3261180 DOI: 10.1371/journal.pone.0030296] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2011] [Accepted: 12/13/2011] [Indexed: 11/20/2022] Open
Abstract
Optimization of the surface charges is a promising strategy for increasing thermostability of proteins. Electrostatic contribution of ionizable groups to the protein stability can be estimated from the differences between the pKa values in the folded and unfolded states of a protein. Using this pKa-shift approach, we experimentally measured the electrostatic contribution of all aspartate and glutamate residues to the stability of a thermophilic ribosomal protein L30e from Thermococcus celer. The pKa values in the unfolded state were found to be similar to model compound pKas. The pKa values in both the folded and unfolded states obtained at 298 and 333 K were similar, suggesting that electrostatic contribution of ionizable groups to the protein stability were insensitive to temperature changes. The experimental pKa values for the L30e protein in the folded state were used as a benchmark to test the robustness of pKa prediction by various computational methods such as H++, MCCE, MEAD, pKD, PropKa, and UHBD. Although the predicted pKa values were affected by crystal contacts that may alter the side-chain conformation of surface charged residues, most computational methods performed well, with correlation coefficients between experimental and calculated pKa values ranging from 0.49 to 0.91 (p<0.01). The changes in protein stability derived from the experimental pKa-shift approach correlate well (r = 0.81) with those obtained from stability measurements of charge-to-alanine substituted variants of the L30e protein. Our results demonstrate that the knowledge of the pKa values in the folded state provides sufficient rationale for the redesign of protein surface charges leading to improved protein stability.
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22
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Sterpone F, Melchionna S. Thermophilic proteins: insight and perspective from in silico experiments. Chem Soc Rev 2011; 41:1665-76. [PMID: 21975514 DOI: 10.1039/c1cs15199a] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Proteins from thermophilic and hyperthermophilic organisms are stable and function at high temperatures (50-100 °C). The importance of understanding the microscopic mechanisms underlying this thermal resistance is twofold: it is key for acquiring general clues on how proteins maintain their fold stable and for targeting those medical and industrial applications that aim at designing enzymes that can work under harsh conditions. In this tutorial review we first provide the general background of protein thermostability by specifically focusing on the structural and thermodynamic peculiarities; next, we discuss how computational studies based on Molecular Dynamics simulations can broaden and refine our knowledge on such special class of proteins.
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Affiliation(s)
- Fabio Sterpone
- Laboratoire de Biochimie Théorique, CNRS, UPR9080, Univ Paris Diderot, Sorbonne Paris Cité, 13 rue Pierre et Marie Curie, 75005, Paris, France.
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23
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Li Y, Zhang J, Tai D, Middaugh CR, Zhang Y, Fang J. PROTS: a fragment based protein thermo-stability potential. Proteins 2011; 80:81-92. [PMID: 21976375 DOI: 10.1002/prot.23163] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2011] [Revised: 07/18/2011] [Accepted: 07/31/2011] [Indexed: 12/30/2022]
Abstract
Designing proteins with enhanced thermo-stability has been a main focus of protein engineering because of its theoretical and practical significance. Despite extensive studies in the past years, a general strategy for stabilizing proteins still remains elusive. Thus effective and robust computational algorithms for designing thermo-stable proteins are in critical demand. Here we report PROTS, a sequential and structural four-residue fragment based protein thermo-stability potential. PROTS is derived from a nonredundant representative collection of thousands of thermophilic and mesophilic protein structures and a large set of point mutations with experimentally determined changes of melting temperatures. To the best of our knowledge, PROTS is the first protein stability predictor based on integrated analysis and mining of these two types of data. Besides conventional cross validation and blind testing, we introduce hypothetical reverse mutations as a means of testing the robustness of protein thermo-stability predictors. In all tests, PROTS demonstrates the ability to reliably predict mutation induced thermo-stability changes as well as classify thermophilic and mesophilic proteins. In addition, this white-box predictor allows easy interpretation of the factors that influence mutation induced protein stability changes at the residue level.
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Affiliation(s)
- Yunqi Li
- Applied Bioinformatics Laboratory, the University of Kansas, Lawrence, Kansas 66047, USA
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24
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Fu H, Grimsley G, Scholtz JM, Pace CN. Increasing protein stability: importance of DeltaC(p) and the denatured state. Protein Sci 2010; 19:1044-52. [PMID: 20340133 DOI: 10.1002/pro.381] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Increasing the conformational stability of proteins is an important goal for both basic research and industrial applications. In vitro selection has been used successfully to increase protein stability, but more often site-directed mutagenesis is used to optimize the various forces that contribute to protein stability. In previous studies, we showed that improving electrostatic interactions on the protein surface and improving the beta-turn sequences were good general strategies for increasing protein stability, and used them to increase the stability of RNase Sa. By incorporating seven of these mutations in RNase Sa, we increased the stability by 5.3 kcal/mol. Adding one more mutation, D79F, gave a total increase in stability of 7.7 kcal/mol, and a melting temperature 28 degrees C higher than the wild-type enzyme. Surprisingly, the D79F mutation lowers the change in heat capacity for folding, DeltaC(p), by 0.6 kcal/mol/K. This suggests that this mutation stabilizes structure in the denatured state ensemble. We made other mutants that give some insight into the structure present in the denatured state. Finally, the thermodynamics of folding of these stabilized variants of RNase Sa are compared with those observed for proteins from thermophiles.
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Affiliation(s)
- Hailong Fu
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843, USA
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25
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Rational stabilization of enzymes by computational redesign of surface charge-charge interactions. Proc Natl Acad Sci U S A 2009; 106:2601-6. [PMID: 19196981 DOI: 10.1073/pnas.0808220106] [Citation(s) in RCA: 177] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Here, we report the application of a computational approach that allows the rational design of enzymes with enhanced thermostability while retaining full enzymatic activity. The approach is based on the optimization of the energy of charge-charge interactions on the protein surface. We experimentally tested the validity of the approach on 2 human enzymes, acylphosphatase (AcPh) and Cdc42 GTPase, that differ in size (98 vs. 198-aa residues, respectively) and tertiary structure. We show that the designed proteins are significantly more stable than the corresponding WT proteins. The increase in stability is not accompanied by significant changes in structure, oligomerization state, or, most importantly, activity of the designed AcPh or Cdc42. This success of the design methodology suggests that it can be universally applied to other enzymes, on its own or in combination with the other strategies based on redesign of the interactions in the protein core.
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