Probing the stability and mechanism for folding of the GrpE1-112 tetrameric deletion mutant of the GrpE protein from E. coli.
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.
Department of Chemistry and The Program in Biochemistry, Knox College, 2 East South St., Galesburg, IL 61401, USA. email@example.com
SourceBiochemical and biophysical research communications 420:3 2012 Apr 13 pg 635-8
Escherichia coli Proteins
Protein Structure, Secondary
Pub Type(s)Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.