title: A cis-encoded sRNA, Hfq and mRNA secondary structure act independently to suppress IS200 transposition.
abstract: IS200 is found throughout Enterobacteriaceae and transposes at a notoriously low frequency. In addition to the transposase protein (TnpA), IS200 encodes an uncharacterized Hfq-binding sRNA that is encoded opposite to the tnpA 5'UTR. In the current work we asked if this sRNA represses tnpA expression. We show here that the IS200 sRNA (named art200 for antisense regulator of transposase IS200) basepairs with tnpA to inhibit translation initiation. Unexpectedly, art200-tnpA pairing is limited to 40 bp, despite 90 nt of perfect complementarity. Additionally, we show that Hfq and RNA secondary structure in the tnpA 5'UTR each repress tnpA expression in an art200-independent manner. Finally, we show that disrupting translational control of tnpA expression leads to increased IS200 transposition in E. coli. The current work provides new mechanistic insight into why IS200 transposition is so strongly suppressed. The possibility of art200 acting in trans to regulate a yet-unidentified target is discussed as well as potential applications of the IS200 system for designing novel riboregulators.
authors.affiliation: Department of Biochemistry, University of Western Ontario, London, ON, N6A 5C1, Canada.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Ellis
authors.affiliation: Department of Biochemistry, University of Western Ontario, London, ON, N6A 5C1, Canada.
authors.forename: Ryan S
authors.initials: RS
authors.lastname: Trussler
authors.affiliation: Department of Biochemistry, University of Western Ontario, London, ON, N6A 5C1, Canada haniford@uwo.ca.
authors.forename: David B
authors.initials: DB
authors.lastname: Haniford
mesh_terms: D004251:DNA Transposable Elements; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism / Q000502:physiology*; D015964:Gene Expression Regulation, Bacterial; D035001:Host Factor 1 Protein / Q000502:physiology*; D009690:Nucleic Acid Conformation; D014176:Protein Biosynthesis; D016372:RNA, Antisense / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000737:chemistry / Q000378:metabolism; D054680:Ribosome Subunits, Small, Bacterial / Q000378:metabolism; D019895:Transposases / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism
chemical_list: D004251:DNA Transposable Elements; D029968:Escherichia coli Proteins; C087373:Hfq protein, E coli; D035001:Host Factor 1 Protein; D016372:RNA, Antisense; D012333:RNA, Messenger; C577316:TnpA(rep) protein, E coli; D019895:Transposases