Polyadenylated mRNA in Escherichia coli: Modulation of poly(A) RNA levels by polynucleotide phosphorylase and ribonuclease II

G. J. Cao, M. Kalapos, N. Sarkar

Research output: Contribution to journalArticle

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Abstract

The effect of 3'-exoribonucleases on the polyadenylation of mRNA in Escherichia coli was studied by comparing the synthesis and levels of poly(A) RNA in wild-type E coli and mutant strains defective in the two major 3'-exoribonucleases: polynucleotide phosphorylase and ribonuclease II. Mutations which substantially reduced the activity of these 3'-exonucleases caused a 10-fold increase in pulse-labeling of total poly(A) RNA in intact cells. When the net rate of RNA synthesis was measured in permeabilized cells, the mutant with defective 3'-exonucleases showed 20- to 60-fold increased synthesis of total poly(A) RNA as well as of specific polyadenylated mRNAs, with less than two-fold changes in non-poly(A) RNA. Measurement of mRNA polyadenylation in permeable cells under conditions when 3'-exoribonucleases were inactive showed a 6-fold higher rate of poly(A) synthesis in the exonuclease-deficient mutant strain, suggesting a higher concentration of mRNA 3'-ends amenable to polyadenylation. Steady-state levels of poly(A) RNA, measured by the ability to serve as template for oligo(dT)-dependent complementary DNA synthesis, also increased more than 40-fold when the 3'-exonucleases were inactivated. Monitoring of the length of the poly(A) tracts by denaturing polyacrylamide gel electrophoresis showed chain lengths of up to 45 residues in the 3'-exonuclease-deficient mutant, whereas most of the poly(A) tracts in the parent strain were shorter than 12 residues. These results show that 3'-exonucleases reduce the level of polyadenylated mRNA in E coli not merely by causing its degradation but also by reducing its rate of synthesis, presumably by competing with poly(A) polymerase for the 3'-ends of mRNA.

Original languageEnglish
Pages (from-to)211-220
Number of pages10
JournalBiochimie
Volume79
Issue number4
DOIs
Publication statusPublished - Apr 1997

Fingerprint

Polyribonucleotide Nucleotidyltransferase
spleen exonuclease
Escherichia coli
Modulation
Messenger RNA
Polyadenylation
Poly A
Polynucleotide Adenylyltransferase
exoribonuclease II
RNA
Exonucleases
Electrophoresis
Chain length
Labeling
Polyacrylamide Gel Electrophoresis
Complementary DNA

Keywords

  • 3'-exonucleases
  • pcnB
  • Poly(A) polymerase
  • RNA degradation
  • RNA synthesis

ASJC Scopus subject areas

  • Biochemistry

Cite this

Polyadenylated mRNA in Escherichia coli : Modulation of poly(A) RNA levels by polynucleotide phosphorylase and ribonuclease II. / Cao, G. J.; Kalapos, M.; Sarkar, N.

In: Biochimie, Vol. 79, No. 4, 04.1997, p. 211-220.

Research output: Contribution to journalArticle

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