RNA chaperones buffer deleterious mutations in E. coli

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Abstract

Both proteins and RNAs can misfold into non-functional conformations. Protein chaperones promote native folding of nascent polypeptides and re-folding of misfolded species, thereby buffering mutations that compromise protein structure and function. Here we show that RNA chaperones can also act as mutation buffers that enhance organismal fitness. Using competition assays, we demonstrate that overexpression of select RNA chaperones, including three DEAD box RNA helicases (CsdA, SrmB, RhlB) and the cold shock protein CspA, improves fitness of two independently evolved E. coli mutator strains that have accumulated deleterious mutations during short- and long-term laboratory evolution. We identify strain-specific mutations that are deleterious and subject to buffering when introduced individually into the ancestral genotype. For DEAD box RNA helicases we show that buffering requires helicase activity, implicating RNA structural remodelling in the buffering process. Our results suggest that RNA chaperones might play a fundamental role in RNA evolution and evolvability.

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Marina Rudan

Mediterranean Institute for Life Sciences, Split, Croatia

Competing interests
The authors declare that no competing interests exist.
Dominique Schneider

Laboratoire Adaptation et Pathogénie des Microorganismes, Université Grenoble Alpes, Grenoble, France

Competing interests
The authors declare that no competing interests exist.
Tobias Warnecke

Molecular Systems Group, MRC Clinical Sciences Centre, Imperial College, London, United Kingdom

For correspondence
tobias.warnecke@csc.mrc.ac.uk

Competing interests
The authors declare that no competing interests exist.
Anita Krisko

Mediterranean Institute for Life Sciences, Split, Croatia

Competing interests
The authors declare that no competing interests exist.

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