Influence of RNA structural stability on the RNA chaperone activity of the Escherichia coli protein StpA.
Proteins with RNA chaperone activity are able to promote folding of RNA molecules by loosening their structure. This RNA unfolding activity is beneficial when resolving misfolded RNA conformations, but could be detrimental to RNAs with low thermodynamic stability. In order to test this idea, we constructed various RNAs with different structural stabilities derived from the thymidylate synthase (td) group I intron and measured the effect of StpA, an Escherichia coli protein with RNA chaperone activity, on their splicing activity in vivo and in vitro. While StpA promotes splicing of the wild-type td intron and of mutants with wild-type-like stability, splicing of mutants with a lower structural stability is reduced in the presence of StpA. In contrast, splicing of an intron mutant, which is not destabilized but which displays a reduced population of correctly folded RNAs, is promoted by StpA. The sensitivity of an RNA towards StpA correlates with its structural stability. By lowering the temperature to 25 degrees C, a temperature at which the structure of these mutants becomes more stable, StpA is again able to stimulate splicing. These observations clearly suggest that the structural stability of an RNA determines whether the RNA chaperone activity of StpA is beneficial to folding.
Grossberger
Rupert
R
Max F. Perutz Laboratories, University Department at the Vienna Biocenter, University of Vienna Dr Bohrgasse 9/5, A-1030 Vienna, Austria.
Mayer
Oliver
O
Waldsich
Christina
C
Semrad
Katharina
K
Urschitz
Sandra
S
Schroeder
Renée
R
D001483:Base Sequence; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D007438:Introns; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D009690:Nucleic Acid Conformation; D012313:RNA / Q000737:chemistry*; D020871:RNA Stability; D013696:Temperature
D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D018832:Molecular Chaperones; C090104:StpA protein, E coli; D012313:RNA