The Escherichia coli heat shock proteins GroEL and GroES modulate the folding of the beta-lactamase precursor.
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.
Laminet
A A
AA
Genzentrum der Universität München, Max-Planck-Institut für Biochemie, Martinsried, FRG.
Ziegelhoffer
T
T
Georgopoulos
C
C
Plückthun
A
A
D004792:Enzyme Precursors / Q000378:metabolism*; D004926:Escherichia coli / Q000378:metabolism*; D006360:Heat-Shock Proteins / Q000378:metabolism*; D007700:Kinetics; D010449:Peptide Mapping; D011487:Protein Conformation; D014357:Trypsin; D001618:beta-Lactamases / Q000378:metabolism*
D004792:Enzyme Precursors; D006360:Heat-Shock Proteins; D014357:Trypsin; C037640:pre-beta-lactamase; D001618:beta-Lactamases