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Metastable structures and refolding kinetics in hok mRNA of plasmid R1

Published online by Cambridge University Press:  01 November 1999

J.H.A. NAGEL
Affiliation:
Leiden Institute of Chemistry, Gorlaeus Laboratories, 2300 RA Leiden, The Netherlands
A.P. GULTYAEV
Affiliation:
Leiden Institute of Chemistry, Gorlaeus Laboratories, 2300 RA Leiden, The Netherlands Section Theoretical Biology and Phylogenetics, Institute of Evolutionary and Ecological Sciences, Leiden University, 2311 GP Leiden, The Netherlands
K. GERDES
Affiliation:
Department of Molecular Biology, Odense University, Dk-5230, Odense M, Denmark
C.W.A. PLEIJ
Affiliation:
Leiden Institute of Chemistry, Gorlaeus Laboratories, 2300 RA Leiden, The Netherlands
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Abstract

Programmed cell death by hok/sok of plasmid R1 and pnd/pndB of R483 mediates plasmid maintenance by killing of plasmid-free cells. It has been previously suggested that premature translation of the plasmid-mediated toxin is prevented during transcription of the hok and pnd mRNAs by the formation of metastable hairpins in the mRNA at the 5′ end. Here, experimental evidence is presented for the existence of metastable structures in the 5′ leader of the hok and pnd mRNAs in vitro. The kinetics of refolding from the metastable to the stable structure in the isolated fragments of the 5′ ends of both the hok and pnd mRNAs could be estimated, in agreement with the structural rearrangement in this region, as predicted to occur during transcription and mRNA activation. The refolding rates of hok and pnd structures are slow enough to allow for the formation of downstream hairpin structures during elongation of the mRNAs, which thereby helps to stabilize the metastable structures. Thus, the kinetic refolding parameters of the hok and pnd mRNAs are consistent with the proposal that the metastable structures prevent premature translation and/or antisense RNA binding during transcription.

Type
Research Article
Copyright
1999 RNA Society

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