title: A thermostable GH45 endoglucanase from yeast: impact of its atypical multimodularity on activity.
abstract: BACKGROUND
  The gene encoding an atypical multi-modular glycoside hydrolase family 45 endoglucanase bearing five different family 1 carbohydrate binding modules (CBM1), designated PpCel45A, was identified in the Pichia pastoris GS115 genome.
  
  
  RESULTS
  PpCel45A (full-length open reading frame), and three derived constructs comprising (i) the catalytic module with its proximal CBM1, (ii) the catalytic module only, and (iii) the five CBM1 modules without catalytic module, were successfully expressed to high yields (up to 2 grams per litre of culture) in P. pastoris X33. Although the constructs containing the catalytic module displayed similar activities towards a range of glucans, comparison of their biochemical characteristics revealed striking differences. We observed a high thermostability of PpCel45A (Half life time of 6 h at 80°C), which decreased with the removal of CBMs and glycosylated linkers. However, both binding to crystalline cellulose and hydrolysis of crystalline cellulose and cellohexaose were substantially boosted by the presence of one CBM rather than five.
  
  
  CONCLUSIONS
  The present study has revealed the specific features of the first characterized endo β-1,4 glucanase from yeast, whose thermostability is promising for biotechnological applications related to the saccharification of lignocellulosic biomass such as consolidated bioprocessing.
authors.affiliation: INRA, UMR 1163 BCF, 13288 Marseille, France.
authors.forename: Marie
authors.initials: M
authors.lastname: Couturier
authors.forename: Julia
authors.initials: J
authors.lastname: Feliu
authors.forename: Mireille
authors.initials: M
authors.lastname: Haon
authors.forename: David
authors.initials: D
authors.lastname: Navarro
authors.forename: Laurence
authors.initials: L
authors.lastname: Lesage-Meessen
authors.forename: Pedro M
authors.initials: PM
authors.lastname: Coutinho
authors.forename: Jean-Guy
authors.initials: JG
authors.lastname: Berrin
mesh_terms: D000595:Amino Acid Sequence; D004795:Enzyme Stability; D005656:Fungal Proteins / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D006026:Glycoside Hydrolases / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D008969:Molecular Sequence Data; D010802:Phylogeny; D010843:Pichia / Q000737:chemistry / Q000145:classification / Q000201:enzymology* / Q000235:genetics; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment
chemical_list: D005656:Fungal Proteins; D006026:Glycoside Hydrolases