Structural and biochemical characterization of a GH3 beta-glucosidase from the probiotic bacteria Bifidobacterium adolescentis

Autor(es)

Florindo, Renata N. ^[1] ; Souza, Valquiria P. ^[2] ; Manzine, Livia R. ^[1] ; Camilo, Cesar M. ^[1] ; Marana, Sandro R. ^[2] ; Polikarpov, Igor ^[1] ; Nascimento, Alessandro S. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Fis Sao Carlos, Av Trabalhador Saocarlense 400, BR-13566590 Sao Carlos, SP - Brazil

^[2] Univ Sao Paulo, Inst Quim, Dept Bioquim, Sao Paulo, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Biochimie; v. 148, p. 107-115, MAY 2018.
• Citações Web of Science: 3

Resumo

Bifidobacterium is an important genus of probiotic bacteria colonizing the human gut. These bacteria can uptake oligosaccharides for the fermentative metabolism of hexoses and pentoses, producing lactate, acetate as well as short-chain fatty acids and propionate. These end-products are known to have important effects on human health. beta-glucosidases (EC 3.2.1.21) are pivotal enzymes for the metabolism and homeostasis of Bifidobacterium, since they hydrolyze small and soluble saccharides, typically producing glucose. Here we describe the cloning, expression, biochemical characterization and the first Xray structure of a GH3 beta-glucosidase from the probiotic bacteria Bifidobacterium adolescentis (BaBgl3). The purified BaBgl3 showed a maximal activity at 45 degrees C and pH 6.5. Under the optimum conditions, BaBgl3 is highly active on 4-nitrophenyl-beta-D-glucopyranoside (pNPG) and, at a lesser degree, on 4-nitrophenyl-beta-D-xylopyranoside (pNPX, about 32% of the activity observed for pNPG). The 2.4 A resolution crystal structure of BaBgl3 revealed a three-domain structure composed of a TIM barrel domain, which together with alpha/beta sandwich domain accommodate the active site and a third C-terminal fibronectin type III (FnIII) domain with unknown function. Modeling of the substrate in the active site indicates that an aspartate interacts with the hydroxyl group of the C6 present in pNPG but absent in pNPX, which explains the substrate preference. Finally, the enzyme is significantly stabilized by glycerol and galactose, resulting in considerable increase in the enzyme activity and its lifetime. The structural and biochemical studies presented here provide a deeper understanding of the molecular mechanisms of complex carbohydrates degradation utilized by probiotic bacteria as well as for the development of new prebiotic oligosaccharides. (C) 2018 Elsevier B.V. and Societe Francaise de Biochimie et Biologie Moleculaire (SFBBM). All rights reserved. (AU)

• Processo FAPESP: 14/19439-5 - Redes estruturais e propriedades funcionais em enzimas
• Beneficiário: Sandro Roberto Marana
• Linha de fomento: Auxílio à Pesquisa - Regular
• Processo FAPESP: 14/06565-2 - Estendendo as fronteiras em interações biomoleculares: docking e avaliação da energia livre
• Beneficiário: Alessandro Silva Nascimento
• Linha de fomento: Auxílio à Pesquisa - Regular
• Processo FAPESP: 08/56255-9 - Structure and function of enzymes and auxiliary proteins from Trichoderma, active in cell-wall hydrolysis
• Beneficiário: Igor Polikarpov
• Linha de fomento: Auxílio à Pesquisa - Programa BIOEN - Temático