Folding and assembly pathways of co-chaperonin proteins 10: Origin of bacterial thermostability.
To compare folding/assembly processes of heptameric co-chaperonin proteins 10 (cpn10) from different species and search for the origin of thermostability in hyper-thermostable Aquifex aeolicus cpn10 (Aacpn10), we have studied two bacterial variants-Aacpn10 and Escherichia coli cpn10 (GroES)-and compared the results to data on Homo sapiens cpn10 (hmcpn10). Equilibrium denaturation of GroES by urea, guanidine hydrochloride (GuHCl) and temperature results in coupled heptamer-to-monomer transitions in all cases. This is similar to the behavior of Aacpn10 but differs from hmcpn10 denaturation in urea. Time-resolved experiments reveal that GroES unfolds before heptamer dissociation, whereas refolding/reassembly begins with folding of individual monomers; these assemble in a slower step. The sequential folding/assembly mechanism for GroES is rather similar to that observed for Aacpn10 but contradicts the parallel paths of hmcpn10. We reveal that Aacpn10's stability profile is shifted upwards, broadened, and also moved horizontally to higher temperatures, as compared to that of GroES.
Luke
Kathryn
K
Department of Biochemistry and Cell Biology, Rice University, 6100 Main Street, Houston, TX 77251, USA.
Wittung-Stafshede
Pernilla
P
D000595:Amino Acid Sequence; D018835:Chaperonin 10 / Q000737:chemistry* / Q000648:ultrastructure*; D003198:Computer Simulation; D004355:Drug Stability; D004926:Escherichia coli / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D008956:Models, Chemical; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011489:Protein Denaturation; D017510:Protein Folding; D020033:Protein Isoforms / Q000737:chemistry / Q000648:ultrastructure; D013045:Species Specificity
D018835:Chaperonin 10; D020033:Protein Isoforms