Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.6 (RNA polymerase)
 34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

4-Thiouridine (s4U), a photoreactive analog of uridine, was randomly incorporated into tRNA2(fMet) precursor molecules by transcription with T7 RNA polymerase. The s4U-containing transcripts were trimmed at their 5'-ends with RNase P RNA to yield mature tRNA2(fMet). The photoreactive tRNA2(fMet) derivatives were aminoacylated and bound to the P site of 70S ribosomes from Escherichia coli in the presence of a poly(A,G,U) template. Irradiation of the complexes at 300 nm resulted in the covalent cross-linking of tRNA2(fMet) to ribosomal proteins and rRNAs within both the 50S and 30S subunits. The labeled proteins were identified as L1, L27, and S19. 50S-subunit proteins L1 and L27 were attached to nucleotide U17 or U17.1 within the D loop of tRNA2(fMet), whereas 30S-subunit protein S19 was cross-linked to nucleotide U47 in the variable loop. Both of these sites occur in or near the central fold of the tRNA. These results permit us to map the D loop of P site-bound tRNA to the region between the central protuberance and the L1 ridge on the 50S ribosomal subunit, while the variable loop can be placed above the cleft on the head of the 30S subunit.
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PMID:Mapping the central fold of tRNA2(fMet) in the P site of the Escherichia coli ribosome. 825 1

4-Thiouridine, a photoreactive analogue of uridine, was randomly incorporated into yeast tRNA(Phe) precursor molecules by transcription with T7 RNA polymerase and the resulting transcripts were converted into mature tRNA(Phe) by treatment with RNase P RNA. The photoreactive tRNA(Phe) was aminoacylated and bound to the P site of Escherichia coli 70S ribosomes in the presence of a poly(U) template. Irradiation of the complexes with light of 300 nm resulted in the covalent crosslinking of nt U20 in the D loop of the tRNA to protein S11 of the 30S ribosomal subunit, whereas nt U33 in the anticodon loop crosslinked to 30S-subunit protein S7. These results allowed us to map the D loop of P site-bound tRNA to the platform of the 30S ribosomal subunit and provided additional information about contacts between protein S7 and the anticodon loop in the cleft between the platform and the subunit head.
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PMID:Photoaffinity labeling of 30S-subunit proteins S7 and S11 by 4-thiouridine-substituted tRNA(Phe) situated at the P site of Escherichia coli ribosomes. 929 1