The Escherichia coli heat shock proteins GroEL and GroES modulate the folding of the beta‐lactamase precursor

• Published in: The EMBO journal 1990-07, Vol.9 (7), p.2315-2319
• Main Authors: Laminet, A. A., Ziegelhoffer, T., Georgopoulos, C., Plückthun, A.
• Format: Article
• Language: English
• Subjects: beta -lactamase; beta-Lactamases - metabolism; Enzyme Precursors - metabolism; Escherichia coli - metabolism; Exact sciences and technology; heat shock proteins; Heat-Shock Proteins - metabolism; Kinetics; Mathematical analysis; Mathematics; Peptide Mapping; Potential theory; Protein Conformation; Sciences and techniques of general use; Trypsin
• ISSN: 0261-4189; 1460-2075
• DOI: 10.1002/j.1460-2075.1990.tb07403.x

One of the fundamental problems in biochemistry is the role of accessory proteins in the process of protein folding. The Escherichia coli heat shock protein complex GroEL/ES has been suggested to be a ‘chaperonin’ and be involved in both oligomer assembly as well as protein transport through the membrane. We show here that the folding of the purified precursor of beta‐lactamase is inhibited by purified GroEL or the GroEL/ES complex with a stoichiometry of one particle per molecule of pre‐beta‐lactamase. Purified GroES alone has no effect on folding. After Mg2+ ATP addition folding resumes and the yield of active enzyme is higher than in the absence of GroEL or GroEL/ES. Unexpectedly, GroEL or GroEL/ES, when added to folded pre‐beta‐lactamase, lead to an apparent net ‘unfolding’, probably to a collapsed state of the protein, which can be reversed by the addition of Mg2+ ATP. The reversible and Mg2+ ATP‐dependent association of GroEL/ES with non‐native proteins might explain its postulated role in both protein transport and oligomer assembly.