title: Structure and function of a novel cellulase 5 from sugarcane soil metagenome.
abstract: Cellulases play a key role in enzymatic routes for degradation of plant cell-wall polysaccharides into simple and economically-relevant sugars. However, their low performance on complex substrates and reduced stability under industrial conditions remain the main obstacle for the large-scale production of cellulose-derived products and biofuels. Thus, in this study a novel cellulase with unusual catalytic properties from sugarcane soil metagenome (CelE1) was isolated and characterized. The polypeptide deduced from the celE1 gene encodes a unique glycoside hydrolase domain belonging to GH5 family. The recombinant enzyme was active on both carboxymethyl cellulose and β-glucan with an endo-acting mode according to capillary electrophoretic analysis of cleavage products. CelE1 showed optimum hydrolytic activity at pH 7.0 and 50 °C with remarkable activity at alkaline conditions that is attractive for industrial applications in which conventional acidic cellulases are not suitable. Moreover, its three-dimensional structure was determined at 1.8 Å resolution that allowed the identification of an insertion of eight residues in the β8-α8 loop of the catalytic domain of CelE1, which is not conserved in its psychrophilic orthologs. This 8-residue-long segment is a prominent and distinguishing feature of thermotolerant cellulases 5 suggesting that it might be involved with thermal stability. Based on its unconventional characteristics, CelE1 could be potentially employed in biotechnological processes that require thermotolerant and alkaline cellulases.
authors.affiliation: Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais, Campinas, São Paulo, Brazil.
authors.forename: Thabata M
authors.initials: TM
authors.lastname: Alvarez
authors.affiliation: Laboratório Nacional de Biociências (LNBio), Centro Nacional de Pesquisa em Energia e Materiais, Campinas, São Paulo, Brazil.
authors.forename: Joice H
authors.initials: JH
authors.lastname: Paiva
authors.affiliation: Laboratório Nacional de Biociências (LNBio), Centro Nacional de Pesquisa em Energia e Materiais, Campinas, São Paulo, Brazil.
authors.forename: Diego M
authors.initials: DM
authors.lastname: Ruiz
authors.affiliation: Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais, Campinas, São Paulo, Brazil.
authors.forename: João Paulo L F
authors.initials: JP
authors.lastname: Cairo
authors.affiliation: Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais, Campinas, São Paulo, Brazil.
authors.forename: Isabela O
authors.initials: IO
authors.lastname: Pereira
authors.affiliation: Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais, Campinas, São Paulo, Brazil.
authors.forename: Douglas A A
authors.initials: DA
authors.lastname: Paixão
authors.affiliation: Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais, Campinas, São Paulo, Brazil.
authors.forename: Rodrigo F
authors.initials: RF
authors.lastname: de Almeida
authors.affiliation: Laboratório Nacional de Biociências (LNBio), Centro Nacional de Pesquisa em Energia e Materiais, Campinas, São Paulo, Brazil.
authors.forename: Celisa C C
authors.initials: CC
authors.lastname: Tonoli
authors.affiliation: Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais, Campinas, São Paulo, Brazil.
authors.forename: Roberto
authors.initials: R
authors.lastname: Ruller
authors.affiliation: Laboratório Nacional de Biociências (LNBio), Centro Nacional de Pesquisa em Energia e Materiais, Campinas, São Paulo, Brazil.
authors.forename: Camila R
authors.initials: CR
authors.lastname: Santos
authors.affiliation: Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais, Campinas, São Paulo, Brazil.
authors.forename: Fabio M
authors.initials: FM
authors.lastname: Squina
authors.affiliation: Laboratório Nacional de Biociências (LNBio), Centro Nacional de Pesquisa em Energia e Materiais, Campinas, São Paulo, Brazil.
authors.forename: Mario T
authors.initials: MT
authors.lastname: Murakami
mesh_terms: D002384:Catalysis; D002480:Cellulase / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D002482:Cellulose / Q000378:metabolism; D003001:Cloning, Molecular; D006863:Hydrogen-Ion Concentration; D054892:Metagenome; D064307:Microbiota / Q000235:genetics; D008958:Models, Molecular; D017434:Protein Structure, Tertiary; D031786:Saccharum / Q000382:microbiology; D012987:Soil / Q000737:chemistry; D012988:Soil Microbiology; D013329:Structure-Activity Relationship
chemical_list: D012987:Soil; D002482:Cellulose; D002480:Cellulase