To investigate the relation between protein stability and the predicted stabilities of individual secondary structural elements, residue Pro86 in an alpha-helix in phage T4 lysozyme was replaced by ten different amino acids. The x-ray crystal structures of seven of the mutant lysozymes were determined at high resolution. In each case, replacement of the proline resulted in the formation of an extended alpha-helix. This involves a large conformational change in residues 81 to 83 and smaller shifts that extend 20 angstroms across the protein surface. Unexpectedly, all ten amino acid substitutions marginally reduce protein thermostability. This insensitivity of stability to the amino acid at position 86 is not simply explained by statistical and thermodynamic criteria for helical propensity. The observed conformational changes illustrate a general mechanism by which proteins can tolerate mutations. Study holds ProTherm entries: 1338, 1339, 1340, 1341, 1342, 1343, 1344, 1345, 1346, 1347, 1348, 1349, 1350, 1351, 1352, 1353, 1354, 1355, 1356 Extra Details: T4 lysozyme; alpha-helix; protein stability; crystal structure;,proline; conformational changes; thermodynamic
Submitter: Connie Wang
Submission Date: April 24, 2018, 8:17 p.m.
|Number of data points||57|
|Proteins||Endolysin ; Endolysin ; Endolysin ; Endolysin ; Endolysin ; Endolysin ; Endolysin ; Endolysin ; Endolysin ; Endolysin|
|Assays/Quantities/Protocols||Experimental Assay: activity pH:6.0 ; Experimental Assay: Tm pH:6.0 ; Experimental Assay: activity pH:4.0 ; Experimental Assay: Tm pH:4.0 ; Experimental Assay: activity pH:2.0 ; Experimental Assay: Tm pH:2.0 ; Derived Quantity: dTm pH:6.0 ; Derived Quantity: dTm pH:4.0 ; Derived Quantity: dTm pH:2.0|
|Libraries||Mutations for sequence MNIFEMLRIDEGLRLKIYKDTEGYYTIGIGHLLTKSPSLNAAKSELDKAIGRNCNGVITKDEAEKLFNQDVDAAVRGILRNAKLKPVYDSLDAVRRCALINMVFQMGETGVAGFTNSLRMLQQKRWDEAAVNLAKSRWYNQTPNRAKRVITTFRTGTWDAYKNL|