Role of hydrogen bond networks and dynamics in positive and negative cooperative stabilization of a protein

Jasmina S. Redzic, Bruce E. Bowler

Research output: Contribution to journalArticlepeer-review

Abstract

Cooperativity mediated through hydrogen bond networks in yeast iso-1-cytochrome c was studied using a thermodynamic triple mutant cycle. Three known stabilizing mutations, Asn 26 to His, Asn 52 to Ile, and Tyr 67 to Phe, were used to construct the triple mutant cycle. The side chain of His 26, a wild-type residue, forms two hydrogen bonds that bridge two substructures of the wild-type protein, and Tyr 67 and Asn 52 are part of an extensive buried hydrogen bond network. The stabilities of all variants in the triple mutant cycle were determined by guanidine hydrochloride denaturation methods and used to determine the pairwise, Δ2Gint, and triple interaction energies. His 26 and Ile 52 interact cooperatively (Δ2Gint is 1-2 kcal/mol), whereas the two other pairs of mutations interact anticooperatively (Δ2G int is -0.5 to -1.5 kcal/mol). Previously reported structural data for iso-1-cytochrome c variants containing these mutations show that changes in the strength of the His 26 to Glu 44 hydrogen bond, apparently caused by changes in main chain dynamics, provide a mechanism for the long distance (His 26 to Phe 67 and His 26 to Ile 52) propagation of pairwise interaction energies. Opposing changes in the strength of the His 26 to Glu 44 hydrogen bond caused by the N52I and Y67F mutations generate a negative triple interaction energy (-0.9 ±0.7 kcal/mol) that combined with cancellation of cooperative and anticooperative pairwise interactions produce apparent additivity for the stabilizing effects of the single mutations in the triple mutant variant.

Original languageEnglish
Pages (from-to)2900-2908
Number of pages9
JournalBiochemistry
Volume44
Issue number8
DOIs
StatePublished - Mar 1 2005

Fingerprint

Dive into the research topics of 'Role of hydrogen bond networks and dynamics in positive and negative cooperative stabilization of a protein'. Together they form a unique fingerprint.

Cite this