Lignocellulose binding of a Cel5A-RtCBM11 chimera with enhanced beta-glucanase activity monitored by electron paramagnetic resonance

Autor(es)

Fonseca-Maldonado, Raquel ^{[1, 2]} ; Meleiro, Luana P. ^[1] ; Mendes, Luis F. S. ^[3] ; Alves, Luana F. ^[4] ; Carli, Sibeli ^[1] ; Morero, Lucas D. ^[3] ; Basso, Luis G. M. ^[3] ; Costa-Filho, Antonio J. ^[3] ; Ward, Richard J. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Fac Filosofia Ciencias & Letras Ribeirao Preto, Dept Quim, Ave Bandeirantes 3900, Ribeirao Preto, SP - Brazil

^[2] Inst Fed Educ Ciencia & Tecnol Sao Paulo IFSP, Dept Gestao, Campus Jacarei, Jacarei, SP - Brazil

^[3] Univ Sao Paulo, Fac Filosofia Ciencias & Letras Ribeirao Preto, Dept Fis, Ribeirao Preto, SP - Brazil

^[4] Univ Sao Paulo, Fac Med Ribeirao Preto, Dept Bioquim, Ribeirao Preto, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: BIOTECHNOLOGY FOR BIOFUELS; v. 10, NOV 14 2017.
• Citações Web of Science: 4

Resumo

Background: The Bacillus subtilis endo-beta-1,4-glucanase (BsCel5A) hydrolyzes beta-1,3-1,4-linked glucan, and the enzyme includes a family 3 carbohydrate-binding module (CBM3) that binds beta-1,4-linked glucan. Methods: Here we investigate the BsCel5A beta-1,3-1,4 glucanase activity after exchanging the CBM3 domain for the family 11 CBM from Ruminiclostridium thermocellum celH (RtCBM11) having beta-1,3-1,4 glucan affinity. Results: The BsCel5A-RtCBM11 presents a 50.4% increase in Vmax, a 10% reduction in K0.5, and a 2.1-fold increase in catalytic efficiency. Enzyme mobility and binding to barley beta-1,3-1,4 glucan and pre-treated sugarcane bagasse were investigated using Electron Paramagnetic Resonance (EPR) with Site-Directed Spin Labeling (SDSL) of the binding site regions of the CBM3 and RtCBM11 domains in the BsCel5A-CBM3 and BsCel5A-RtCBM11, respectively. Although higher mobility than the RtCBM11 was shown, no interaction of the spin-labeled CBM3 with beta-1,3-1,4 glucan was observed. In contrast, a Ka value of 0.22 mg/mL was estimated from titration of the BsCel5A-RtCBM11 with beta-1,3-1,4 glucan. Enzyme binding as inferred from altered EPR spectra of the BsCel5A-RtCBM11 was observed only after xylan or lignin extraction from sugarcane bagasse. Binding to xylan-or lignin-free lignocellulose was correlated with a 4.5-to 5-fold increase in total reducing sugar release as compared to the milled intact sugarcane bagasse, suggesting that xylan impedes enzyme access to the beta-1,3-1,4 glucan. Conclusions: These results show that the non-specific binding of the BsCel5A-RtCBM11 to the lignin component of the cell wall is minimal, and represent the first reported use of EPR to directly study the interaction of glycoside hydrolyse enzymes with natural insoluble substrates. (AU)

• Processo FAPESP: 14/50884-5 - INCT 2014: Instituto Nacional de Ciência e Tecnologia do Bioetanol
• Beneficiário: Marcos Silveira Buckeridge
• Linha de fomento: Auxílio à Pesquisa - Temático
• Processo FAPESP: 10/18850-2 - Identificação, caracterização e engenharia de enzimas que degradam a parede celular das plantas
• Beneficiário: Richard John Ward
• Linha de fomento: Auxílio à Pesquisa - Temático
• Processo FAPESP: 15/18390-5 - Ressonância magnética eletrônica em biofísica molecular: novos e velhos olhares para novos e velhos problemas
• Beneficiário: Antonio José da Costa Filho
• Linha de fomento: Auxílio à Pesquisa - Regular
• Processo FAPESP: 15/18149-6 - Estudo das mudanças conformacionais e funcionais do domínio catalítico e do CBM (Carbohydrate Binding Module) de uma endoglucanase GH5 durante a catálise.
• Beneficiário: Raquel Fonseca Maldonado
• Linha de fomento: Bolsas no Brasil - Pós-Doutorado