N Nakajima

Publications (2)37.18 Total impact

• Source

  Available from: jbc.org

  Article: In vitro transcription of the supB-E tRNA operon of Escherichia coli. Characterization of transcription products.

  N Nakajima, H Ozeki, Y Shimura
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  ABSTRACT: The seven tRNA genes clustered in the supB-E region of the Escherichia coli chromosome were transcribed in vitro with purified RNA polymerase, using a restriction fragment from lambda psu degrees 2, a transducing phage carrying the chromosome region, as template. A single major transcript was synthesized, which was about 770 nucleotides long and contained all seven tRNA sequences. The terminal sequences of the transcript were determined and mapped on the DNA sequence of the supB-E region previously determined. The transcription start site is seven base pairs downstream from the Pribnow box sequence, as expected from the DNA sequence analysis and consistent with the findings on the trimeric tRNA precursor (pppG--tRNAMETM-tRNALeu-tRNAGln1) which was detected in an RNase P mutant and shown to be coded for by the supB-E region. Cleavage of the restriction fragment at the -35 region with another restriction endonuclease abolished the template activity of the fragment. Transcription of the supB-E tRNA operon was relatively unaffected by the presence of rho factor. Transcription termination occurs within a region of three bases between positions 770 and 772 from the transcription start site. Immediately upstream from the termination sites, there is a region of 26 nucleotides that could form a stem structure, thereby consistent with the general feature of rho-independent termination sites.
  Journal of Biological Chemistry 10/1982; 257(18):11113-20. · 4.77 Impact Factor
• Article: Organization and structure of an E. coli tRNA operon containing seven tRNA genes.

  N Nakajima, H Ozeki, Y Shimura
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  ABSTRACT: The structure and organization on the Escherichia coli chromosome of the gene cluster coding for two methionine tRNAs (tRNAmMet), four glutamine tRNAs (two tRNA1Gln and two tRNA2Gln), and a previously unidentified tRNA (called tRNAx) have been studied by restriction enzyme analysis and DNA sequencing, utilizing a specialized transducing bacteriophage (lambda psu degrees 2) carrying the supB-supE region. From the sequence analysis, the previously unidentified tRNA has been shown to have an anticodon sequence (5'-UAG-3') corresponding to a leucine codon. The organization of this tRNA gene cluster on the E. coli chromosome is tRNAmMet-9 base pairs-tRNAx-23 base pairs-tRNA1Gln-34 base pairs-tRNA1Gln-15 base pairs-tRNAmMet-47 base pairs-tRNA2Gln-37 base pairs-tRNA2Gln. The duplicated genes coding for tRNAmMet, tRNA,Gln, and tRNA2Gln have identical sequences, which are the same as the sequences determined previously with tRNA molecules. These tRNA sequences are preceded by a single promoter region where a "Pribnow box" sequence is present seven base pairs upstream from the transcription start site. The spacer regions separating the seven tRNA sequences are different from each other both in size and in nucleotide sequence. The possible implication of these sequences for precursor processing is discussed. A restriction fragment that has been originally identified in lambda psu degrees 2 DNA and shown to contain the seven tRNA genes has been detected in the E. coli chromosome, thereby suggesting that this tRNA gene cluster is present in the bacterial genome with the same organization as in the transducing phage genome.
  Cell 02/1981; 23(1):239-49. · 32.40 Impact Factor