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Physical and functional interactions among RNase E, polynucleotide phosphorylase and the cold‐shock protein, CsdA: evidence for a ‘cold shock degradosome’
Author(s) -
Prud’hommeGénéreux Annie,
Beran Rudolf K.,
Iost Isabelle,
Ramey C. Shane,
Mackie George A.,
Simons Robert W.
Publication year - 2004
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2004.04360.x
Subject(s) - degradosome , polynucleotide phosphorylase , cold shock domain , rnase p , biology , rna , rna helicase a , exosome complex , helicase , translation (biology) , ribonucleoprotein , microbiology and biotechnology , messenger rna , biochemistry , enzyme , gene , purine nucleoside phosphorylase , purine
Summary 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°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.