Unusually long-lived pause required for regulation of a Rho-dependent transcription terminator

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 111; no. 19; pp. E1999 - E2007
• Main Authors: Hollands, Kerry, Sevostiyanova, Anastasia, Groisman, Eduardo A.
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 13.05.2014; National Acad Sciences
• Series: PNAS Plus
• Subjects: Adenosine Triphosphatases - genetics; Bacteria; Bacterial Proteins - genetics; Base Sequence; Biological Sciences; DNA-Directed RNA Polymerases - genetics; Gene Expression Regulation, Bacterial; genes; Genetics; longevity; magnesium; Magnesium - metabolism; Membrane Transport Proteins - genetics; Molecular Sequence Data; Nucleic Acid Conformation; Nucleic acids; nucleotide sequences; PNAS Plus; Rho Factor - genetics; Ribonucleic acid; Riboswitch - genetics; RNA; RNA, Bacterial - chemistry; RNA, Bacterial - genetics; RNA, Messenger - chemistry; RNA, Messenger - genetics; Salmonella enterica; Salmonella enterica - genetics; Terminator Regions, Genetic - genetics; magnesium; RNA polymerase
• ISSN: 0027-8424; 1091-6490; 1091-6490
• DOI: 10.1073/pnas.1319193111

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.