Oligomerization as a strategy for cold adaptation: Structure and dynamics of the GH1 beta-glucosidase from Exiguobacterium antarcticum B7

Author(s)

Zanphorlin, Leticia Maria ^[1] ; de Giuseppe, Priscila Oliveira ^[2] ; Honorato, Rodrigo Vargas ^[2] ; Costa Tonoli, Celisa Caldana ^[2] ; Fattori, Juliana ^[2] ; Crespim, Elaine ^[1] ; Lopes de Oliveira, Paulo Sergio ^[2] ; Ruller, Roberto ^[1] ; Murakami, Mario Tyago ^[2]

Affiliation

^[1] Brazilian Bioethanol Sci & Technol Lab, Sao Paulo - Brazil

^[2] Natl Ctr Res Energy & Mat, Brazilian Biosci Natl Lab, Sao Paulo - Brazil

• Document type: Journal article
• Source: SCIENTIFIC REPORTS; v. 6, MAR 31 2016.
• Web of Science Citations: 20

Abstract

Psychrophilic enzymes evolved from a plethora of structural scaffolds via multiple molecular pathways. Elucidating their adaptive strategies is instrumental to understand how life can thrive in cold ecosystems and to tailor enzymes for biotechnological applications at low temperatures. In this work, we used X-ray crystallography, in solution studies and molecular dynamics simulations to reveal the structural basis for cold adaptation of the GH1 beta-glucosidase from Exiguobacterium antarcticum B7. We discovered that the selective pressure of low temperatures favored mutations that redesigned the protein surface, reduced the number of salt bridges, exposed more hydrophobic regions to the solvent and gave rise to a tetrameric arrangement not found in mesophilic and thermophilic homologues. As a result, some solvent-exposed regions became more flexible in the cold-adapted tetramer, likely contributing to enhance enzymatic activity at cold environments. The tetramer stabilizes the native conformation of the enzyme, leading to a 10-fold higher activity compared to the disassembled monomers. According to phylogenetic analysis, diverse adaptive strategies to cold environments emerged in the GH1 family, being tetramerization an alternative, not a rule. These findings reveal a novel strategy for enzyme cold adaptation and provide a framework for the semi-rational engineering of beta-glucosidases aiming at cold industrial processes. (AU)

• FAPESP's process: 13/13309-0 - Studies of the structural and functional behavior of enzymes evolutionarily specialized in the degradation of plant biomass with potential biotechnological applications
• Grantee: Mário Tyago Murakami
• Support Opportunities: Regular Research Grants
• FAPESP's process: 14/07135-1 - Multi-user equipament approved in grant 2013/13309-0: Beckman Coulter capillary electrophoresis systems with LIF detection system
• Grantee: Mário Tyago Murakami
• Support Opportunities: Multi-user Equipment Program