A transposon-derived small RNA regulates gene expression in Salmonella Typhimurium.
Bacterial sRNAs play an important role in regulating many cellular processes including metabolism, outer membrane homeostasis and virulence. Although sRNAs were initially found in intergenic regions, there is emerging evidence that protein coding regions of the genome are a rich reservoir of sRNAs. Here we report that the 5΄UTR of IS200 transposase mRNA (tnpA) is processed to produce regulatory RNAs that affect expression of over 70 genes in Salmonella Typhimurium. We provide evidence that the tnpA derived sRNA base-pairs with invF mRNA to repress expression. As InvF is a transcriptional activator of SPI-1 encoded and other effector proteins, tnpA indirectly represses these genes. We show that deletion of IS200 elements in S. Typhimurium increases invasion in vitro and reduces growth rate, while over-expression of tnpA suppresses invasion. Our work indicates that tnpA acts as an sRNA 'sponge' that sets a threshold for activation of Salmonella pathogenicity island (SPI)-1 effector proteins and identifies a new class of 'passenger gene' for bacterial transposons, providing the first example of a bacterial transposon producing a regulatory RNA that controls host gene expression.
Department of Biochemistry, University of Western Ontario, London, Ontario N6A 5C1, Canada.
Michael J
MJ
Ellis
Department of Biochemistry, University of Western Ontario, London, Ontario N6A 5C1, Canada.
Ryan S
RS
Trussler
Department of Biochemistry, University of Western Ontario, London, Ontario N6A 5C1, Canada.
Onella
O
Charles
Department of Biochemistry, University of Western Ontario, London, Ontario N6A 5C1, Canada.
David B
DB
Haniford
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D004251:DNA Transposable Elements / Q000235:genetics*; D015536:Down-Regulation / Q000235:genetics; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D012329:RNA, Bacterial / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012486:Salmonella typhimurium / Q000235:genetics* / Q000254:growth & development; D017423:Sequence Analysis, RNA
D001426:Bacterial Proteins; D004251:DNA Transposable Elements; D012329:RNA, Bacterial; D012333:RNA, Messenger