title: Ion specific influences on the stability and unfolding transitions of a naturally aggregating protein; RecA.
abstract: The Escherichia coli RecA protein is a naturally aggregated protein complex that is affected by the presence of salts. In order to gain further insight into the nature of the ion-interactions on a naturally aggregating protein we used circular dichroism (CD), fluorescence and dynamic light scattering (DLS) to study the effects of different concentrations of MgCl2, CaCl2, NaCl, Na2SO4, and MgSO4 on RecA structure and thermal unfolding. The results show unique ion influences on RecA structure, aggregation, unfolding transitions and stability and the anion effects correlate with the reverse Hofmeister series. The mechanisms of the ion-induced changes most likely result from specific ion binding, changes in the interfacial tension and altered protein-solvent interactions that may be especially important for protein-protein interactions in naturally aggregating proteins. The presence of some ions leads to the formation of RecA complexes that are resistant to complete denaturation and nonspecific aggregation.
authors.affiliation: Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, VA 22807, United States.
authors.forename: William R
authors.initials: WR
authors.lastname: Cannon
authors.forename: Nathaniel D
authors.initials: ND
authors.lastname: Talley
authors.forename: Brittany A
authors.initials: BA
authors.lastname: Danzig
authors.forename: Xiaomei
authors.initials: X
authors.lastname: Liu
authors.forename: Jennifer S
authors.initials: JS
authors.lastname: Martinez
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Shreve
authors.forename: Gina
authors.initials: G
authors.lastname: MacDonald
mesh_terms: D002942:Circular Dichroism; D004926:Escherichia coli / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000378:metabolism; D007477:Ions / Q000737:chemistry*; D008027:Light; D055550:Protein Stability; D058767:Protein Unfolding; D011938:Rec A Recombinases / Q000737:chemistry* / Q000378:metabolism; D012492:Salts / Q000737:chemistry; D012542:Scattering, Radiation; D013696:Temperature
chemical_list: D029968:Escherichia coli Proteins; D007477:Ions; D012492:Salts; D011938:Rec A Recombinases