Small molecule inhibition of a Group II chaperonin: pinpointing a loop region within the equatorial domain as necessary for protein refolding.
The functionality of regions within the equatorial domain of Group II chaperonins is poorly understood. Previously we showed that a 70 amino acid sequence within this domain on the single-subunit recombinant thermosome from Methanocaldococcus jannaschii (rTHS) contains residues directly responsible for refolding protein substrates [L.M. Bergeron, C. Lee, D.S. Clark, Identification of a critical chaperoning region on an archaeal recombinant thermosome, Biochem. Biophys. Res. Commun. 369 (2008) 707-711]. In the present study, 6-aminopenicillanic acid (6-APA) was found to bind to rTHS and inhibit it from refolding proteins. Fluorescence anisotropy was used to measure a 6-APA/rTHS dissociation constant of 17.1 microM and verify that the binding site is within the first 70 amino-terminal rTHS residues. Docking simulations point to a specific loop region at residues 53-57 on rTHS as the most likely binding region. This loop region is located within the oligomeric association sites of the wild-type thermosome. These results implicate a specific equatorial region of Group II chaperonins in the refolding of proteins, and suggest its importance in conformational changes that accompany chaperone function.
Bergeron
Lisa M
LM
Department of Chemical Engineering, University of California, Berkeley, CA 94720, USA.
Shis
David L
DL
Gomez
Lizabeth
L
Clark
Douglas S
DS
D019843:Archaeal Proteins / Q000737:chemistry*; D018833:Chaperonins / Q000737:chemistry*; D005454:Fluorescence Polarization; D017016:Methanococcaceae / Q000378:metabolism*; D008958:Models, Molecular; D018832:Molecular Chaperones / Q000737:chemistry*; D010397:Penicillanic Acid / Q000031:analogs & derivatives / Q000737:chemistry; D011485:Protein Binding; D011487:Protein Conformation; D017510:Protein Folding; D056405:Thermosomes
D019843:Archaeal Proteins; D018832:Molecular Chaperones; D010397:Penicillanic Acid; D018833:Chaperonins; D056405:Thermosomes; C004408:aminopenicillanic acid