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. Study holds ProTherm entries: 17560, 17561, 17562, 17563 Extra Details: deletion mutant; site-directed mutagenesis; circular dichroism; solution X-ray scattering; inhibitor-induced folding; DNA hydrolysis
Submitter: Connie Wang
Submission Date: April 24, 2018, 8:49 p.m.
|Number of data points||8|
|Proteins||Thermonuclease ; Thermonuclease|
|Assays/Quantities/Protocols||Experimental Assay: Tm ; Experimental Assay: dHvH ; Experimental Assay: dG ; Derived Quantity: dTm ; Derived Quantity: ddG|
|Libraries||Mutations for sequence ATSTKKLHKEPATLIKAIDGDTVKLMYKGQPMTFRLLLVDTPETKHPKKGVEKYGPEASAFTKKMVENAKKIEVEFDKGQRTDKYGRGLAYIYADGKMVNEALVRQGLAKVAYVYKPNNTHEQHLRKSEAQAKKEKLNIWSEDNADSGQ|