High-level overexpression, rapid purification, and properties of Escherichia coli tRNA nucleotidyltransferase

H. Cudny, M. P. Deutscher

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27 Scopus citations

Abstract

The cloned Escherichia coli cca gene, described in the accompanying paper (Cudny, H., Lupski, J.R., Godson, G.N., and Deutscher, M.P. (1986) J. Biol. Chem. 261, 6444-6449), has been used to construct strains that overproduce tRNA nucleotidyltransferase, the enzyme that synthesizes the CCA terminus of tRNA. Strain UT481 (pEC4), which contains a 1.9-kilobase cca gene insert in plasmid pUC8, overproduces the enzyme by about 100-150-fold, probably under the control of the cca gene promoter. A second strain, containing a plasmid with a 1.5-kilobase insert, overproduces tRNA nucleotidyltransferase by about 650-fold, to a level of about 3-4% of the soluble cell protein. In this case, overexpression was dependentt on the lac promoter of the plasmid. A rapid, two-step procedure was developed to purify large amounts of the enzyme from strain UT481 (pEC4) that was about 40% pure, free of ribonucleases, and suitable for use as a reagent for modification of tRNA molecules. Preparation of milligram quantities of homogeneous tRNA nucleotidyltransferase was accomplished by two further chromatographic steps. The structural and catalytic properties of this purified enzyme were similar to those from partially purified preparations previously described. The availability of large amounts of pure tRNA nucleotidyltransferase will now permit a variety of structural and functional studies of the enzymes that previously were not possible.

Original languageEnglish (US)
Pages (from-to)6450-6453
Number of pages4
JournalJournal of Biological Chemistry
Volume261
Issue number14
StatePublished - 1986

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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