title: Probing the stability and mechanism for folding of the GrpE1-112 tetrameric deletion mutant of the GrpE protein from E. coli.
abstract: Insight into the stability and folding of oligomeric proteins is essential to the understanding of protein folding, especially since the majority of proteins found in nature are oligomeric. A deletion mutant of the GrpE protein from Escherichia coli, that contains the first 112 residues (GrpE1-112) of 197 total, is an oligomeric protein forming a tetrameric structure. A four-helix bundle structure is formed via the interaction of an α-helix (22 amino acids in length) from each monomer. Using both thermal and chemical (urea) denaturation studies, the GrpE1-112 protein has rather low stability with a T(m) of unfolding of 37 °C, a C(m) (urea) of 1.3M, and a ΔG(unfolding) of 8.4 kJ mol(-1). Investigation into the folding pathway using circular dichroism (CD) stopped-flow revealed a two step process with a fast first phase (k(refolding)=8.0 × 10(6)s(-1)M(-1)) forming a multimeric intermediate that possesses significant α-helical content followed by a slow, first order, step forming the folded tetramer.
authors.affiliation: Department of Chemistry and The Program in Biochemistry, Knox College, 2 East South St., Galesburg, IL 61401, USA. amehl@knox.edu
authors.forename: Andrew F
authors.initials: AF
authors.lastname: Mehl
authors.forename: Kelby
authors.initials: K
authors.lastname: Okada
authors.forename: Shirley M
authors.initials: SM
authors.lastname: Dehn
authors.forename: Sarah
authors.initials: S
authors.lastname: Kurian
mesh_terms: D002942:Circular Dichroism; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics*; D006360:Heat-Shock Proteins / Q000737:chemistry* / Q000235:genetics*; D008956:Models, Chemical; D017510:Protein Folding; D055503:Protein Multimerization; D055550:Protein Stability; D017433:Protein Structure, Secondary; D017384:Sequence Deletion
chemical_list: D029968:Escherichia coli Proteins; C489400:GrpE protein, E coli; D006360:Heat-Shock Proteins