The role of surface salt bridges in protein stabilization has been a source of controversy. Here we present the NMR structure of a hyperthermophilic rubredoxin variant (PFRD-XC4) and the thermodynamic analysis of two surface salt bridges by double mutant cycles. This analysis shows that the surface side chain to side chain salt bridge between Lys 6 and Glu 49 does not stabilize PFRD-XC4. The main chain to side chain salt bridge between the N-terminus and Glu 14 was, however, found to stabilize PFRD-XC4 by 1. 5 kcal mol(-)(1). The entropic cost of making a surface salt bridge involving the protein's backbone is reduced, since the backbone has already been immobilized upon protein folding. Study holds ProTherm entries: 7918, 7919, 7920, 7921, 7922, 7923, 7924, 7925, 7926, 7927, 7928, 7929, 7930, 7931, 7932, 7933, 7934, 7935, 7936, 7937, 7938, 7939, 7940, 7941, 7942 Extra Details: surface salt bridges; protein stabilization; hyperthermophilic,rubredoxin; protein folding
Submitter: Connie Wang
Submission Date: April 24, 2018, 8:35 p.m.
|Number of data points||57|
|Proteins||Rubredoxin ; Rubredoxin|
|Assays/Quantities/Protocols||Experimental Assay: Cm ; Experimental Assay: m ; Experimental Assay: dG ; Experimental Assay: Cm ; Experimental Assay: m ; Experimental Assay: dG ; Experimental Assay: Tm|
|Libraries||Mutations for sequence AKWVCKICGYIYDEDAGDPDNGISPGTKFEELPDDWVCPICGAPKSEFEKLED|