TY - JOUR
T1 - Over Expression of a tRNALeu Isoacceptor Changes Charging Pattern of Leucine tRNAs and Reveals New Codon Reading
AU - Sørensen, Michael Askvad
AU - Elf, J.
AU - Bouakaz, E.
AU - Tenson, T.
AU - Sanyal, S.
AU - Björk, G. R.
AU - Ehrenberg, M.
N1 - Keywords: aminoacylation; systems biology; decoding; staruation; kinetics
PY - 2005
Y1 - 2005
N2 - During mRNA translation, synonymous codons for one amino acid areoften read by different isoaccepting tRNAs. The theory of selective tRNAcharging predicts greatly varying percentages of aminoacylation amongisoacceptors in cells starved for their common amino acid. It also predictsmajor changes in tRNA charging patterns upon concentration changes ofsingle isoacceptors, which suggests a novel type of translational control ofgene expression. We therefore tested the theory by measuring withNorthern blots the charging of Leu-tRNAs in Escherichia coli under Leulimitation in response to over expression of tRNALeuGAG. As predicted, thecharged level of tRNALeuGAG increased and the charged levels of four otherLeu isoacceptors decreased or remained unchanged, but the charged levelof tRNALeuUAG increased unexpectedly. To remove this apparent inconsistencybetween theory and experiment we postulated a previouslyunknown common codon for tRNALeuGAG and tRNALeuUAG. Subsequently, wedemonstrated that the tRNALeuGAG codon CUU is, in fact, read also bytRNALeuUAG, due to a uridine-5-oxyacetic acid modification.
AB - During mRNA translation, synonymous codons for one amino acid areoften read by different isoaccepting tRNAs. The theory of selective tRNAcharging predicts greatly varying percentages of aminoacylation amongisoacceptors in cells starved for their common amino acid. It also predictsmajor changes in tRNA charging patterns upon concentration changes ofsingle isoacceptors, which suggests a novel type of translational control ofgene expression. We therefore tested the theory by measuring withNorthern blots the charging of Leu-tRNAs in Escherichia coli under Leulimitation in response to over expression of tRNALeuGAG. As predicted, thecharged level of tRNALeuGAG increased and the charged levels of four otherLeu isoacceptors decreased or remained unchanged, but the charged levelof tRNALeuUAG increased unexpectedly. To remove this apparent inconsistencybetween theory and experiment we postulated a previouslyunknown common codon for tRNALeuGAG and tRNALeuUAG. Subsequently, wedemonstrated that the tRNALeuGAG codon CUU is, in fact, read also bytRNALeuUAG, due to a uridine-5-oxyacetic acid modification.
U2 - 10.1016/j.jmb.2005.08.076
DO - 10.1016/j.jmb.2005.08.076
M3 - Journal article
C2 - 16236318
SN - 0022-2836
VL - 354
SP - 16
EP - 24
JO - Journal of Molecular Biology
JF - Journal of Molecular Biology
IS - 1
ER -