1
|
Jacomini D, Bussler L, Corrêa JM, Kadowaki MK, Maller A, da-Conceição Silva JL, Simão RDCG. Cloning, expression and characterization of C. crescentus xynA2 gene and application of Xylanase II in the deconstruction of plant biomass. Mol Biol Rep 2020; 47:4427-4438. [PMID: 32424521 DOI: 10.1007/s11033-020-05507-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2020] [Accepted: 05/08/2020] [Indexed: 11/24/2022]
Abstract
Biotechnology offers innovative alternatives for industrial bioprocesses mainly because it uses enzymes that biodegrade the hemicellulose releasing fermentable sugars. Caulobacter crescentus (C. crescentus) has seven genes responsible for xylanolytic cleavage, 5 to β-xylosidases (EC 3.2.1.37) and 2 for endoxylanases, like xynA2 (CCNA_03137) that encodes Xylanase II (EC 3.2.1.8) of the glycohydrolases-GH10 group. The xynA2 gene was amplified by PCR, cloned into the pTrcHisA vector e efficiently overexpressed in E. coli providing a His-tag fusion protein. Recombinant xylanase (XynA2) was purified by affinity chromatography using a nickel sepharose column and exhibited a single 43 kDa band on SDS-PAGE gel. XynA2 showed an optimum alkaline pH (8) and stability at alkaline pH for 24 h. Although C. crescentus is mesophilic, XynA2 has optimum temperature of 60 °C and is thermo-resistance at 65 °C. XynA maintains 66% of the enzymatic activity at high temperatures (90 °C) without being denatured.The enzyme displayed a xylanolitic activity free of cellulase to xylan from beechwood and it was not inhibited in the presence of 50 μmol mL-1 of xylose. In addition, dithiothreitol (DTT) induced XynA2 activity, as it improved its kinetic parameters by lowering the KM (5.78 μmol mL-1) and increasing the KCat/KM ratio (1.63 U s-1). Finally, C. crescentus XynA2 efficiently hydrolyzed corn straw with high release of reducing sugars that can be applied in different branches of the industry.
Collapse
Affiliation(s)
- Débora Jacomini
- Laboratório de Bioquímica Molecular, Centro de Ciências Exatas e Tecnológicas, Universidade Estadual do Oeste do Paraná, Cascavel,, Paraná, 85814-110, Brazil
| | - Larissa Bussler
- Laboratório de Bioquímica Molecular, Centro de Ciências Exatas e Tecnológicas, Universidade Estadual do Oeste do Paraná, Cascavel,, Paraná, 85814-110, Brazil
| | - Juliana Moço Corrêa
- Laboratório de Bioquímica Molecular, Centro de Ciências Médicas e Farmacêuticas, Universidade Estadual do Oeste do Paraná, Rua Universitária, 2069, Cascavel, PR, 85814-110, Brazil
| | - Marina Kimiko Kadowaki
- Laboratório de Bioquímica Molecular, Centro de Ciências Médicas e Farmacêuticas, Universidade Estadual do Oeste do Paraná, Rua Universitária, 2069, Cascavel, PR, 85814-110, Brazil
| | - Alexandre Maller
- Laboratório de Bioquímica Molecular, Centro de Ciências Médicas e Farmacêuticas, Universidade Estadual do Oeste do Paraná, Rua Universitária, 2069, Cascavel, PR, 85814-110, Brazil
| | - José Luis da-Conceição Silva
- Laboratório de Bioquímica Molecular, Centro de Ciências Médicas e Farmacêuticas, Universidade Estadual do Oeste do Paraná, Rua Universitária, 2069, Cascavel, PR, 85814-110, Brazil
| | - Rita de Cássia Garcia Simão
- Laboratório de Bioquímica Molecular, Centro de Ciências Exatas e Tecnológicas, Universidade Estadual do Oeste do Paraná, Cascavel,, Paraná, 85814-110, Brazil. .,Laboratório de Bioquímica Molecular, Centro de Ciências Médicas e Farmacêuticas, Universidade Estadual do Oeste do Paraná, Rua Universitária, 2069, Cascavel, PR, 85814-110, Brazil.
| |
Collapse
|
2
|
Azouz RAM, Hegazy UM, Said MM, Bassuiny RI, Salem AM, Fahmy AS. Improving the catalytic efficiency of thermostable Geobacillus stearothermophilus xylanase XT6 by single-amino acid substitution. J Biochem 2020; 167:203-215. [PMID: 31617574 DOI: 10.1093/jb/mvz086] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Accepted: 10/02/2019] [Indexed: 01/09/2023] Open
Abstract
Directed evolution using error-prone polymerase chain reaction was employed in the current study to enhance the catalytic efficiency of a thermostable Geobacillus stearothermophilus xylanase XT6 parent. High-throughput screening identified two variants with enhanced activity. Sequencing analysis revealed the presence of a single-amino acid substitution (P209L or V161L) in each variant. The maximum activity of mutant V161L and P209L was at 85°C and 70°C, respectively. Both mutants exhibited maximum activity at pH 7. The thermal and alkaline tolerance of mutant V161L only were markedly improved. The two mutants were more resistant to ethanol inhibition than the parent. Substrate specificity of the two mutants was shifted from beechwood xylan to birchwood xylan. The potential of the two mutants to hydrolyze rice straw and sugarcane bagasse increased. Both turnover number (kcat) and catalytic efficiency (kcat/kM) increased 12.2- and 5.7-folds for variant P209L and 13- and 6.5-folds for variant V161L, respectively, towards birchwood xylan. Based on the previously published crystal structure of extracellular G. stearothermophilus xylanase XT6, V161L and P209L mutation locate on βα-loops. Conformational changes of the respective loops could potentiate the loop swinging, product release and consequently result in enhancement of the catalytic performance.
Collapse
Affiliation(s)
- Rasha A M Azouz
- Genetic Engineering and Biotechnology Research Division, Molecular Biology Department, National Research Centre, El-Behouth Street, Dokki, 12622 Giza, Egypt
| | - Usama M Hegazy
- Genetic Engineering and Biotechnology Research Division, Molecular Biology Department, National Research Centre, El-Behouth Street, Dokki, 12622 Giza, Egypt
| | - Mahmoud M Said
- Faculty of Science, Department of Biochemistry, Ain Shams University, El-Khalyfa El-Mamoun Street, Abbasya, 11566 Cairo, Egypt
| | - Roqaya I Bassuiny
- Genetic Engineering and Biotechnology Research Division, Molecular Biology Department, National Research Centre, El-Behouth Street, Dokki, 12622 Giza, Egypt
| | - Ahmed M Salem
- Faculty of Science, Department of Biochemistry, Ain Shams University, El-Khalyfa El-Mamoun Street, Abbasya, 11566 Cairo, Egypt
| | - Afaf S Fahmy
- Genetic Engineering and Biotechnology Research Division, Molecular Biology Department, National Research Centre, El-Behouth Street, Dokki, 12622 Giza, Egypt
| |
Collapse
|