Unusually long-lived pause required for regulation of a Rho-dependent transcription terminator.
Up to half of all transcription termination events in bacteria rely on the RNA-dependent helicase Rho. However, the nucleic acid sequences that promote Rho-dependent termination remain poorly characterized. Defining the molecular determinants that confer Rho-dependent termination is especially important for understanding how such terminators can be regulated in response to specific signals. Here, we identify an extraordinarily long-lived pause at the site where Rho terminates transcription in the 5'-leader region of the Mg(2+) transporter gene mgtA in Salmonella enterica. We dissect the sequence elements required for prolonged pausing in the mgtA leader and establish that the remarkable longevity of this pause is required for a riboswitch to stimulate Rho-dependent termination in the mgtA leader region in response to Mg(2+) availability. Unlike Rho-dependent terminators described previously, where termination occurs at multiple pause sites, there is a single site of transcription termination directed by Rho in the mgtA leader. Our data suggest that Rho-dependent termination events that are subject to regulation may require elements distinct from those operating at constitutive Rho-dependent terminators.
Department of Microbial Pathogenesis andYale Microbial Diversity Institute, West Haven, CT 06516Howard Hughes Medical Institute, Yale School of Medicine, New Haven, CT 06536; and.
Kerry
K
Hollands
Department of Microbial Pathogenesis and.
Anastasia
A
Sevostiyanova
Department of Microbial Pathogenesis andYale Microbial Diversity Institute, West Haven, CT 06516Howard Hughes Medical Institute, Yale School of Medicine, New Haven, CT 06536; and eduardo.groisman@yale.edu.
Eduardo A
EA
Groisman
D000251:Adenosine Triphosphatases / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D012321:DNA-Directed RNA Polymerases / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D008274:Magnesium / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D012329:RNA, Bacterial / Q000737:chemistry / Q000235:genetics; D012333:RNA, Messenger / Q000737:chemistry / Q000235:genetics; D012234:Rho Factor / Q000235:genetics*; D058928:Riboswitch / Q000235:genetics*; D019779:Salmonella enterica / Q000235:genetics*; D013728:Terminator Regions, Genetic / Q000235:genetics*
D001426:Bacterial Proteins; D026901:Membrane Transport Proteins; D012329:RNA, Bacterial; D012333:RNA, Messenger; D012234:Rho Factor; D058928:Riboswitch; D012321:DNA-Directed RNA Polymerases; C113275:RNA polymerase alpha subunit; D000251:Adenosine Triphosphatases; C093585:MgtA protein, bacteria; D008274:Magnesium
RNA polymerase; magnesium