1 Regulation of Escherichia coli polynucleotide phosphorylase by ATP Marta

Regulation of Escherichia coli polynucleotide phosphorylase by ATP.

Polynucleotide phosphorylase (PNPase), an enzyme conserved in bacteria and eukaryotic organelles, processively catalyzes the phosphorolysis of RNA, releasing nucleotide diphosphates, and the reverse polymerization reaction. In Escherichia coli, both reactions are implicated in RNA decay, as addition of either poly(A) or heteropolymeric tails targets RNA to degradation. PNPase may also be associ...

RNase III - independent autogenous regulation of Escherichia coli polynucleotide phosphorylase 1 via translational repression 2 3

Polynucleotide phosphorylase functions both as a 3* 3 5* exonuclease and a poly(A) polymerase in Escherichia coli

In vitro, polynucleotide phosphorylase of Escherichia coli can both synthesize RNA by using nucleotide diphosphates as precursors and exonucleolytically degrade RNA in the presence of inorganic phosphate. However, because of the high in vivo concentration of inorganic phosphate in exponentially growing cells, it has been assumed that the enzyme works exclusively as an exonuclease. Here we demon...

Characterization of polynucleotide phosphorylase mutants of Escherichia coli.

Three polynucleotide phosphorylase mutations, isolated in heavily mutagenized Escherichia coli strains Q7, Q13, and Q27, were characterized after their transfer by P1 transduction to nearly isogenic strains which lack ribonuclease I. Each strain has a different altered form of polynucleotide phosphorylase. One enzyme exhibited sharply reduced activity under all conditions tested. A second had r...

Isolation and mapping of polynucleotide phosphorylase mutants of Escherichia coli.

Three strains of Escherichia coli with altered polynucleotide phosphorylase, Q7, Q13, and Q27, were isolated by screening clones from heavily mutagenized cultures for low levels of the enzyme. The three mutations were found to cotransduce with argG and asp, and the pnp locus which they define was mapped with respect to these loci. An explanation for the nonreciprocal cotransduction frequencies ...