We have characterized the properties of a set of variants of the N-terminal domain of lambda repressor bearing disruptive mutations in the hydrophobic core. These mutations include some that dramatically alter the total core residue volume (by up to six methylene groups) and some that place a single polar residue into the otherwise hydrophobic core. The structural properties of the purified proteins have been studied by CD spectroscopy, biological activity, recognition by conformation-specific monoclonal antibodies, and 1H NMR spectroscopy. The stabilities of the proteins have been measured by thermal and guanidine hydrochloride denaturation. Proteins with disruptive core mutations are found to display a continuum of increasingly nonnative properties. Large internal volume changes cause both significant conformational rearrangements and destabilization by up to 5 kcal/mol. Variants with polar substitutions at core positions no longer behave like well-folded proteins but rather display characteristics of molten globules. However, even proteins bearing some of the most disruptive mutations retain many of the crude secondary and tertiary structural features of the wild-type protein. These results indicate that primitive elements of native structure can form in the absence of normal core packing. Study holds ProTherm entries: 207, 208, 209, 210, 211, 212, 213, 214, 215, 2170, 2171, 2172, 2173, 2174, 2175, 2176, 2177, 2178, 2179, 2180, 2181, 2182, 2183, 2184, 2185, 2186, 2187, 2188, 2189, 2190 Extra Details: lambda repressor; hydrophobic core; CD spectroscopy;,energetic consequences
Submitter: Connie Wang
Submission Date: April 24, 2018, 8:14 p.m.
|Number of data points||124|
|Proteins||Repressor protein cI ; Repressor protein cI ; Repressor protein cI|
|Assays/Quantities/Protocols||Experimental Assay: Tm ; Experimental Assay: Cm temp:5.0 C ; Experimental Assay: m temp:5.0 C ; Experimental Assay: dG_H2O temp:5.0 C ; Experimental Assay: activity ; Experimental Assay: Cm temp:25.0 C ; Experimental Assay: m temp:25.0 C ; Experimental Assay: dG_H2O temp:25.0 C ; Derived Quantity: dTm ; Derived Quantity: ddG_H2O temp:5.0 C ; Derived Quantity: ddG_H2O temp:25.0 C|
|Libraries||Mutations for sequence STKKKPLTQEQLEDARRLKAIYEKKKNELGLSQESVADKMGMGQSGVGALFNGINALNAYNAALLAKILKVSVEEFSPSIAREIYEMYEAVS|