title: Role of exposed aromatic residues in substrate-binding of CBM family 5 chitin-binding domain of alkaline chitinase.
abstract: Chitinase J (ChiJ) from alkaliphilic Bacillus sp. strain J813 has a multidomain structure containing a catalytic domain (CatD), a fibronectin type III like domain (FnIIID) and a chitin-binding domain (ChBD). It has been shown that the ChBD binds to an insoluble chitin and enhances its degradation by the CatD. Further binding study of the ChBD was performed with a glutathione-S-transferase fusion protein. This fusion protein showed binding abilities to insoluble chitin and chitosan. Two surface-exposed aromatic residues (Trp541 and Trp542) were found in the tertiary-structure model of ChBD and targeted for mutational analysis. Single and double mutations of the two aromatic residues decreased the chitin- and chitosan-binding abilities. It was revealed that these residues would be important for substrate-binding of the ChBD.
authors.affiliation: Department of Bioengineering, Tokyo Institute of Technology, Yokohama 226-8501, Japan. uni.f.aa@m.titech.ac.jp
authors.forename: Fumiya
authors.initials: F
authors.lastname: Uni
authors.forename: Sunmi
authors.initials: S
authors.lastname: Lee
authors.forename: Rie
authors.initials: R
authors.lastname: Yatsunami
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Fukui
authors.forename: Satoshi
authors.initials: S
authors.lastname: Nakamura
mesh_terms: D002686:Chitin / Q000378:metabolism*; D002688:Chitinases / Q000737:chemistry* / Q000378:metabolism; D048271:Chitosan / Q000378:metabolism; D005982:Glutathione Transferase / Q000235:genetics; D009154:Mutation; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D040681:Structural Homology, Protein; D014364:Tryptophan / Q000737:chemistry*
chemical_list: D011993:Recombinant Fusion Proteins; D002686:Chitin; D014364:Tryptophan; D048271:Chitosan; D005982:Glutathione Transferase; D002688:Chitinases