title: Oligomerization as a strategy for cold adaptation: Structure and dynamics of the GH1 β-glucosidase from Exiguobacterium antarcticum B7.
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 β-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 β-glucosidases aiming at cold industrial processes.
authors.affiliation: Brazilian Bioethanol Science and Technology Laboratory, Campinas, São Paulo, Brazil.
authors.forename: Leticia Maria
authors.initials: LM
authors.lastname: Zanphorlin
authors.affiliation: Brazilian Biosciences National Laboratory from the National Center for Research in Energy and Materials, Campinas, São Paulo, Brazil.
authors.forename: Priscila Oliveira
authors.initials: PO
authors.lastname: de Giuseppe
authors.affiliation: Brazilian Biosciences National Laboratory from the National Center for Research in Energy and Materials, Campinas, São Paulo, Brazil.
authors.forename: Rodrigo Vargas
authors.initials: RV
authors.lastname: Honorato
authors.affiliation: Brazilian Biosciences National Laboratory from the National Center for Research in Energy and Materials, Campinas, São Paulo, Brazil.
authors.forename: Celisa Caldana Costa
authors.initials: CC
authors.lastname: Tonoli
authors.affiliation: Brazilian Biosciences National Laboratory from the National Center for Research in Energy and Materials, Campinas, São Paulo, Brazil.
authors.forename: Juliana
authors.initials: J
authors.lastname: Fattori
authors.affiliation: Brazilian Bioethanol Science and Technology Laboratory, Campinas, São Paulo, Brazil.
authors.forename: Elaine
authors.initials: E
authors.lastname: Crespim
authors.affiliation: Brazilian Biosciences National Laboratory from the National Center for Research in Energy and Materials, Campinas, São Paulo, Brazil.
authors.forename: Paulo Sergio Lopes
authors.initials: PS
authors.lastname: de Oliveira
authors.affiliation: Brazilian Bioethanol Science and Technology Laboratory, Campinas, São Paulo, Brazil.
authors.forename: Roberto
authors.initials: R
authors.lastname: Ruller
authors.affiliation: Brazilian Biosciences National Laboratory from the National Center for Research in Energy and Materials, Campinas, São Paulo, Brazil.
authors.forename: Mario Tyago
authors.initials: MT
authors.lastname: Murakami
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics*; D059001:Aquatic Organisms; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D003001:Cloning, Molecular; D003080:Cold Temperature; D018360:Crystallography, X-Ray; D004795:Enzyme Stability; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D000068536:Bacillota / Q000145:classification / Q000201:enzymology* / Q000235:genetics; D015870:Gene Expression; D057927:Hydrophobic and Hydrophilic Interactions; D007700:Kinetics; D056004:Molecular Dynamics Simulation; D010802:Phylogeny; D000072417:Protein Domains; D055503:Protein Multimerization; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013816:Thermodynamics; D001617:beta-Glucosidase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D011994:Recombinant Proteins; D001617:beta-Glucosidase