Abstract

Thermodynamic properties of a mutant lambda Cro repressor with Cys replacing Val55 were studied calorimetrically. Formation of the S-S cross-link between neighboring Cys55 residues in this dimeric molecule leads to stabilization of a structure formed by the C-terminal parts of the two polypeptide chains, which behave as a single cooperative domain upon protein denaturation by heating. This composite domain is very stable at neutral pH and disrupts at 110 degrees C. The S-S-cross-linked tryptic fragment (residues 22-66), which includes this C-terminal domain, has similar stability. The N-terminal parts of the polypeptide chains do not form any stable structure when isolated, but in S-S-cross-linked dimer, they form a single cooperative block which melts in an all-or-none way 9 degrees C higher than the un-cross-linked protein. The observed cooperation of the distant N-terminal parts in dimer raises questions regarding lambda Cro repressor structure in solution. Study holds ProTherm entries: 5311, 5312, 5313, 5314, 5315, 5316, 5317, 5318, 5319 Extra Details: dimeric molecule; single cooperative domain; S-S-cross-linked

Submission Details

ID: zDqzXLgE

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:29 p.m.

Version: 1

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