| 1. |
- Faxén, Margareta, et al.
(författare)
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Is efficiency of suppressor tRNAs controlled at the level of ribosomal proofreading in vivo?
- 1988
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Ingår i: Journal of Bacteriology. - 0021-9193 .- 1098-5530. ; 170:8, s. 3756-3760
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Tidskriftsartikel (refereegranskat)abstract
- Ribosomal rpsD mutations did not stimulate nonsense suppressor tRNAs in a general manner according to their increased ribosomal ambiguity and decreased proofreading efficiency. Streptomycin, which stimulates error production by blocking proofreading in vitro, did not increase efficiency of suppressor tRNAs in strains with normal or streptomycin-resistant (rpsL) ribosomes. It did so only in combination with one rpsL mutation which is associated with streptomycin pseudodependence.
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| 2. |
- Glemarec, C, et al.
(författare)
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The NMR structure of 31-mer RNA domain of E. coli RNase P RNA using its non-uniformly deuterium labelled counterpart (the "NMR-window" concept)
- 1996
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Ingår i: Nucleic Acids Research. - : Oxford University Press (OUP). - 0305-1048 .- 1362-4962. ; 24:11, s. 2022-2035
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Tidskriftsartikel (refereegranskat)abstract
- The NMR structure of a 31mer RNA constituting a functionally important domain of the catalytic RNase P RNA from Escherichia coli is reported. Severe spectral overlaps of the proton resonances in the natural 31mer RNA (1) were successfully tackled by unique spectral simplifications found in the partially-deuterated 31 mer RNA analogue (2) incorporating deuterated cytidines [C5 (>95 atom % 2H), C2' (>97 atom % 2H), C3' (>97 atom % 2H), C4' (>65 atom % 2H) and C5' (>97 atom % 2H)] [for the 'NMR-window' concept see: Földesi,A. et al. (1992) Tetrahedron, 48, 9033; Foldesi,A. et al. (1993) J. Biochem. Biophys. Methods, 26, 1; Yamakage,S.-I. et al. (1993) Nucleic Acids Res., 21, 5005; Agback,P. et al. (1994) Nucleic Acids Res., 22, 1404; Földesi,A. et al. (1995) Tetrahedron, 51, 10065; Földesi,A. et al. (1996) Nucleic Acids Res., 24, 1187-1194]. 175 resonances have been assigned out of total of 235 non-exchangeable proton resonances in (1) in an unprecedented manner in the absence of 13C and 15N labelling. 41 out of 175 assigned resonances could be accomplished with the help of the deuterated analogue (2). The two stems in 31mer RNA adopt an A-type RNA conformation and the base-stacking continues from stem I into the beginning of the loop I. Long distance cross-strand NOEs showed a structured conformation at the junction between stem I and loop I. The loop I-stem II junction is less ordered and shows structural perturbation at and around the G11 -C22 base pair.
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| 3. |
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| 4. |
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| 5. |
- Kirsebom, Leif A, et al.
(författare)
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Effects of growth conditions and mutations in RNA polymerase on translational activity in vitro in Escherichia coli
- 1980
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Ingår i: Molecular General Genetics. - 0026-8925 .- 1432-1874. ; 180:1, s. 27-33
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Tidskriftsartikel (refereegranskat)abstract
- The translational capacity in vitro in Escherichia coli, using RNA from phage R17 or Q beta as messenger, is several times higher if the extracts are prepared from cells harvested in early exponential phase or grown under conditions of good aeration compared to if extracts are prepared from cells harvested in a later growth phase or grown under semi-aerobic conditions. In low activity extracts the production of phage replicase protein is preferentially affected. Growth of a wild type strain under semi-aerobic conditions has a less pronounced effect on translational capacity in vitro using crude mRNA from normal or T4 infected cells or with poly(U). Mutants were fortuitously found which did not show a lowered translational activity in vitro as a result of entering late phase of growth. Two of these were changed in RNA polymerase. Two different translational inhibitors can be demonstrated in the ribosomal wash fraction obtained from semi-aerobically grown wild type cells, whereas only one was found in the case of aerobically grown cells. The low translational activity of semi-aerobically grown cells in vitro is implied to be dependent on the induction or activation of a translational inhibitor. It behaves like a protein but is not likely to be a protease or RNAse.
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| 6. |
- Kirsebom, Leif A, et al.
(författare)
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Functional interactions in vivo between suppressor tRNA and mutationally altered ribosomal protein S4
- 1986
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Ingår i: Molecular General Genetics. - 0026-8925 .- 1432-1874. ; 205:2, s. 240-247
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Tidskriftsartikel (refereegranskat)abstract
- Ribosomal mutants (rpsD) which are associated with a generally increased translational ambiguity were investigated for their effects in vivo on individual tRNA species using suppressor tRNAs as models. It was found that nonsense suppression is either increased, unaffected or decreased depending on the codon context and the rpsD allele involved as well as the nature of the suppressor tRNA. Missense suppression of AGA and AGG by glyT(SuAGA/G) tRNA as well as UGG by glyT(SuUGG-8) tRNA is unaffected whereas suppression of UGG by glyT(SuUGA/G) or glyV(SuUGA/G) tRNA is decreased in the presence of an rpsD mutation. The effects on suppressor tRNA are thus not correlated with the ribosomal ambiguity (Ram) phenotype of the rpsD mutants used in this study. It is suggested that the mutationally altered ribosomes are changed in functional interactions with the suppressor tRNA itself rather than with the competing translational release factor(s) or cognate aminoacyl tRNA. The structure of suppressor tRNA, particularly the anticodon loop, and the suppressed codon as well as the codon context determine the allele specific functional interactions with these ribosomal mutations.
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| 7. |
- Kirsebom, Leif A, et al.
(författare)
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Involvement of ribosomal protein L7/L12 in control of translational accuracy
- 1985
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - 0027-8424 .- 1091-6490. ; 82:3, s. 717-721
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Tidskriftsartikel (refereegranskat)abstract
- The effects of two mutations, which map at the rplL locus and both give a changed 50S ribosomal protein L7/L12, were studied. Both mutations are associated with an increased misreading of all three nonsense codons in vivo and ribosomes from the mutants give an increased misreading of the phenylalanine codon UUU by tRNALeu in vitro. The rplL-associated misreading in vitro is not limited to a particular type of mRNA or tRNA. Results from a translational proofreading assay, using mutant ribosomes, suggest that protein L7/L12 is involved in the control of translational accuracy by contributing to the efficiency of a translational proofreading step(s).
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| 8. |
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| 9. |
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| 10. |
- Altman, S, et al.
(författare)
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Cleavage of RNA by RNase P from E. coli
- 1987
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Ingår i: Molecular Biology of RNA: New Perspectives. - : Academic Press.
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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