Ribosomes and ribosomal RNA as chaperones for folding of proteins.
BACKGROUND
Provocative recent reports indicate that the large subunits of either prokaryotic or eukaryotic ribosomes have the capacity to promote refolding of denatured enzymes.


RESULTS
Salt-washed Escherichia coli ribosomes are shown to promote refolding of denatured rhodanese. The ability of the ribosomes to carry out renaturation is a property of the 50S ribosomal subunit, specifically the 23S rRNA. Refolding and release of enzymatically active rhodanese leaves the ribosomes in an inactive state or conformation for subsequent rounds refolding. Inactive ribosomes can be activated by elongation factor G (EF-G) plus GTP or by cleavage of their 23S rRNA by alpha-sarcin. Activation by either mechanism is strongly inhibited by the EF-G.GDP.fusidic acid complex.


CONCLUSIONS
Large subunits of E. coli ribosomes, specifically 23S rRNA, have the capacity to mediate refolding of denatured rhodanese. Refolding activity is related to the state or conformation of ribosomes that is promoted by EF-G. Activation by either mechanism is strongly inhibited by the EF-G.GDP.fusidic acid complex.
Kudlicki
W
W
Department of Chemistry and Biochemistry, University of Texas at Austin 78712, USA.
Coffman
A
A
Kramer
G
G
Hardesty
B
B
D004722:Endoribonucleases / Q000378:metabolism; D004789:Enzyme Activation; D004926:Escherichia coli / Q000378:metabolism; D005656:Fungal Proteins; D005672:Fusidic Acid / Q000494:pharmacology; D006160:Guanosine Triphosphate / Q000378:metabolism; D018832:Molecular Chaperones / Q000378:metabolism*; D020653:Peptide Elongation Factor G; D010445:Peptide Elongation Factors / Q000378:metabolism; D017510:Protein Folding; D011500:Protein Synthesis Inhibitors / Q000378:metabolism; D012335:RNA, Ribosomal / Q000378:metabolism*; D012270:Ribosomes / Q000378:metabolism*; D013883:Thiostrepton / Q000494:pharmacology; D013884:Thiosulfate Sulfurtransferase / Q000378:metabolism*
D005656:Fungal Proteins; D018832:Molecular Chaperones; D020653:Peptide Elongation Factor G; D010445:Peptide Elongation Factors; D011500:Protein Synthesis Inhibitors; D012335:RNA, Ribosomal; C014801:alpha-sarcin; D005672:Fusidic Acid; D006160:Guanosine Triphosphate; D013884:Thiosulfate Sulfurtransferase; D004722:Endoribonucleases; D013883:Thiostrepton