Physical and functional interactions among RNase E, polynucleotide phosphorylase and the cold-shock protein, CsdA: evidence for a 'cold shock degradosome'.
Escherichia coli contains at least five ATP-dependent DEAD-box RNA helicases which may play important roles in macromolecular metabolism, especially in translation and mRNA decay. Here we demonstrate that one member of this family, CsdA, whose expression is induced by cold shock, interacts physically and functionally with RNase E. Three independent approaches show that after a shift of cultures to 15 degrees C, CsdA co-purifies with RNase E and other components of the RNA degradosome. Moreover, functional assays using reconstituted minimal degradosomes prepared from purified components in vitro show that CsdA can fully replace the resident RNA helicase of the RNA degradosome, RhlB. In addition, under these conditions, CsdA displays RNA-dependent ATPase activity. Taken together, our data are consistent with a model in which CsdA accumulates during the early stages of cold acclimatization and subsequently assembles into degradosomes with RNase E synthesized in cold-adapted cultures. These findings show that the RNA degradosome is a flexible macromolecular machine capable of adapting to altered environmental conditions.
Prud'homme-Généreux
Annie
A
Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, V6T 1Z3, Canada.
Beran
Rudolf K
RK
Iost
Isabelle
I
Ramey
C Shane
CS
Mackie
George A
GA
Simons
Robert W
RW
D000222:Adaptation, Physiological; D000251:Adenosine Triphosphatases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D003080:Cold Temperature; D053487:DEAD-box RNA Helicases; D004722:Endoribonucleases / Q000378:metabolism*; D004926:Escherichia coli / Q000502:physiology*; D029968:Escherichia coli Proteins / Q000378:metabolism*; D009097:Multienzyme Complexes / Q000378:metabolism*; D011117:Polyribonucleotide Nucleotidyltransferase / Q000378:metabolism*; D011485:Protein Binding; D020365:RNA Helicases / Q000378:metabolism*
D029968:Escherichia coli Proteins; D009097:Multienzyme Complexes; C111244:degradosome; D000255:Adenosine Triphosphate; D011117:Polyribonucleotide Nucleotidyltransferase; D004722:Endoribonucleases; C022537:ribonuclease E; D000251:Adenosine Triphosphatases; C027900:RNA-dependent ATPase; C088840:deaD protein, E coli; D053487:DEAD-box RNA Helicases; D020365:RNA Helicases