title: Role of C-terminal region of Staphylococcal nuclease for foldability, stability, and activity.
abstract: The role of the C-terminal region of Staphylococcal nuclease (SNase) was examined by deletion mutation. Deletions up to eight residues do not affect the structure and function. The structure and enzymatic activity were partially lost by deleting Ser141-Asn149 (Delta141-149), and deletion of Trp140-Asn149 (Delta140-149) resulted in further loss of structure and activity. A 13-residue deletion showed the same effect as the 10-residue deletion. Both Ser141Gln and Ser141Ala mutations for an eight-residue deletion mutant did not alter properties as well as Ser141A1a for full-length SNase. In contrast, Trp140Ala mutation for Delta141-149 shows the same effect as the deletion of Trp140. Trp140Ala mutation for full-length SNase causes the loss of native structure. These observations indicate the significance of the 140th and the 141st residues. The side-chain of the 140th residue is required to be tryptophan; however, the backbone of the 141st residue is solely critical for foldability, but the side-chain information is not crucial. All of the mutants that take a non-native conformation show enzymatic activity and inhibitor-induced folding, suggesting that foldability is required for the activity.
authors.affiliation: Graduate School of Materials Science, Nara Institute of Science and Technology, Ikoma, Nara, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Hirano
authors.forename: Ken'ichi
authors.initials: K
authors.lastname: Mihara
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Yamazaki
authors.forename: Hironari
authors.initials: H
authors.lastname: Kamikubo
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Imamoto
authors.forename: Mikio
authors.initials: M
authors.lastname: Kataoka
mesh_terms: D000595:Amino Acid Sequence; D002942:Circular Dichroism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004795:Enzyme Stability; D008836:Micrococcal Nuclease / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D011487:Protein Conformation; D011489:Protein Denaturation; D017510:Protein Folding; D017384:Sequence Deletion; D013816:Thermodynamics; D013942:Thymine Nucleotides / Q000494:pharmacology
chemical_list: D004791:Enzyme Inhibitors; D013942:Thymine Nucleotides; C019111:thymidine 3',5'-diphosphate; D008836:Micrococcal Nuclease