Studies on structural stability of thermophilic Sulfolobus acidocaldarius ribosomes
Yangala, K.; Suryanarayana, T.
Indian Journal of Biochemistry and Biophysics 44(1): 19-25
2007
ISSN/ISBN: 0301-1208 PMID: 17385336 Document Number: 614180
Structural stability of thermophilic archaeon Sulfolobus acidocaldarius ribosomes, with respect their susceptibility to pancreatic RNase A and stability to temperature (Delta T-m), on treatment with various stabilizing (polyamines) and destabilizing, (sulfhydryl and intercalating) agents were studied and compared with mesophilic E. coli ribosomes, to understand the Structural differences between thermophilic and mesophilic ribosomes. Thermophilic archaeal ribosomes and their subunits were 10-times less susceptible to pancreatic RNase A, compared to mesophilic ribosomes, showing the presence of strong and compact Structural organization in them. Thermophilic ribosomes treated with destabilizing agents, such as sulfhydryl reagents [5,5'-Dithio-bis-(2-nitrobenzoic acid), N-ethylinalcimide and p- hydroxy-lCUrybenzoatc) and intercalating agents (ethidiLlin bromide, EtBr) showed higher stability to RNase A, compared to similarly treated mesophilic ribosonles, indicating the unavailability of' thiol-reactive groups and the presence of' strong solvent inaccessible inner core. Higher stability of thermophilic ribosornes compared to rnesophilic ribosomes to untolding agents like Urea f'U1-thC1- Supported the presence o17 strong inner core particle. Thermophilic ribosomes treated with intercalating agents, such as EtBr were less Susceptible to RNasc A, though they bound to more reagent, showing the rigidity or resilience of' their macromolecular structure to alterations caused by destabilizing agents. Overall, these results indicated that I'actors Such as presence of'strong solvent inaccessible inner core and rigidity of' ribosorne macromolecular structure contributed stability of' therniophilic ribosonics to RNasc A and other destabilizing agents, when compared to inesophilic ribosomes.