Tn10/IS10 transposition is downregulated at the level of transposase expression by the RNA-binding protein Hfq.
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.
Ross
Joseph A
JA
Department of Biochemistry, University of Western Ontario, London, Ontario, Canada.
Wardle
Simon J
SJ
Haniford
David B
DB
D004251:DNA Transposable Elements; D015536:Down-Regulation; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D015971:Gene Expression Regulation, Enzymologic; D035001:Host Factor 1 Protein / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D014176:Protein Biosynthesis; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D019895:Transposases / Q000235:genetics* / Q000378:metabolism
D004251:DNA Transposable Elements; D029968:Escherichia coli Proteins; C087373:Hfq protein, E coli; D035001:Host Factor 1 Protein; D016601:RNA-Binding Proteins; C095509:IS10 transposase; D019895:Transposases