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.

Links

Publisher Full Text

Authors

Mehl AF, Okada K, Dehn SM, Kurian S

Institution

Department of Chemistry and The Program in Biochemistry, Knox College, 2 East South St., Galesburg, IL 61401, USA. amehl@knox.edu

Source

Biochemical and biophysical research communications 420:3 2012 Apr 13 pg 635-8

MeSH

Circular Dichroism
Escherichia coli Proteins
Heat-Shock Proteins
Models, Chemical
Protein Folding
Protein Multimerization
Protein Stability
Protein Structure, Secondary
Sequence Deletion

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.

Language

eng

PubMed ID

22450325