Polynucleotide phosphorylase: Not merely an RNase but a pivotal post-transcriptional regulator

Hypoxia: not merely a regulator of angiogenesis?

Introduction Maintaining oxygen homeostasis is of vital importance for the survival and development of mammalian cells. Hypoxia (below-normal levels of oxygen in air, blood and tissue) can potentially lead to cellular dysfunction and ultimately cell death and is a feature of many pathological conditions. Understanding how reduced oxygen levels may contribute to or even promote disease is a sign...

Mammalian polynucleotide phosphorylase is an intermembrane space RNase that maintains mitochondrial homeostasis.

We recently identified polynucleotide phosphorylase (PNPase) as a potential binding partner for the TCL1 oncoprotein. Mammalian PNPase exhibits exoribonuclease and poly(A) polymerase activities, and PNPase overexpression inhibits cell growth, induces apoptosis, and stimulates proinflammatory cytokine production. A physiologic connection for these anticancer effects and overexpression is difficu...

An essential function for the phosphate-dependent exoribonucleases RNase PH and polynucleotide phosphorylase.

Escherichia coli cells lacking both polynucleotide phosphorylase (PNPase) and RNase PH, the only known P(i)-dependent exoribonucleases, were previously shown to grow slowly at 37 degrees C and to display a dramatically reduced level of tRNA(Tyr)su3+ suppressor activity. Here we show that the RNase PH-negative, PNP-negative double-mutant strain actually displays a reversible cold-sensitive pheno...

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

RNase activity of polynucleotide phosphorylase is critical at low temperature in Escherichia coli and is complemented by RNase II.

In Escherichia coli, the cold shock response is exerted upon a temperature change from 37 degrees C to 15 degrees C and is characterized by induction of several cold shock proteins, including polynucleotide phosphorylase (PNPase), during acclimation phase. In E. coli, PNPase is essential for growth at low temperatures; however, its exact role in this essential function has not been fully elucid...