Biochemistry Publications

Title

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

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.