Tn10/IS10 Transposition Is Downregulated at the Level of Transposase Expression by the RNA-binding Protein Hfq

Authors

Joseph A. Ross, The University of Western Ontario
Simon J. Wardle, The University of Western Ontario
David B. Haniford, The University of Western Ontario

Document Type

Article

Publication Date

11-2010

Journal

Molecular Microbiology

Volume

78

Issue

3

First Page

607

Last Page

621

URL with Digital Object Identifier

http://dx.doi.org/10.1111/j.1365-2958.2010.07359.x

Abstract

We show in this work that disruption of the hfq gene in Escherichia coli causes a large increase in IS10 transposition when IS10 is present on a multi-copy plasmid. Hfq is an RNA-binding protein that regulates the expression of a large number of genes at the post-transcriptional level by promoting the pairing of mRNAs with partially complementary short RNAs. As the translation of IS10 transposase mRNA (RNA-IN) is inhibited by an IS10-encoded anti-sense RNA (RNA-OUT), it seemed likely that Hfq would negatively regulate Tn10/IS10 transposition by promoting anti-sense inhibition of RNA-IN translation. Consistent with this, we show that Hfq promotes pairing of RNA-IN and RNA-OUT in vitro and downregulates RNA-IN expression in vivo. However, we also show that Hfq negatively regulates Tn10 transposition when no functional anti-sense RNA is produced. Taken together, the results suggest that Hfq acts at two distinct steps to inhibit Tn10/IS10 transposition. This is the first example of Hfq regulating a bacterial transposition reaction.