title: A bacterial mRNA leader that employs different mechanisms to sense disparate intracellular signals.
abstract: Bacterial mRNAs often contain leader sequences that respond to specific metabolites or ions by altering expression of the associated downstream protein-coding sequences. Here we report that the leader RNA of the Mg(2+) transporter gene mgtA of Salmonella enterica, which was previously known to function as a Mg(2+)-sensing riboswitch, harbors an 18 codon proline-rich open reading frame-termed mgtL-that permits intracellular proline to regulate mgtA expression. Interfering with mgtL translation by genetic, pharmacological, or environmental means was observed to increase the mRNA levels from the mgtA coding region. Substitution of the mgtL proline codons by other codons abolished the response to proline and to hyperosmotic stress but not to Mg(2+). Our findings show that mRNA leader sequences can consist of complex regulatory elements that utilize different mechanisms to sense separate signals and mediate an appropriate cellular response.
authors.affiliation: Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110, USA.
authors.forename: Sun-Yang
authors.initials: SY
authors.lastname: Park
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Cromie
authors.forename: Eun-Jin
authors.initials: EJ
authors.lastname: Lee
authors.forename: Eduardo A
authors.initials: EA
authors.lastname: Groisman
mesh_terms: D020121:5' Untranslated Regions; D000251:Adenosine Triphosphatases / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D015964:Gene Expression Regulation, Bacterial; D008274:Magnesium / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D011392:Proline / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D038621:Regulatory Sequences, Ribonucleic Acid; D012486:Salmonella typhimurium / Q000235:genetics* / Q000378:metabolism; D016415:Sequence Alignment; D014158:Transcription, Genetic
chemical_list: D020121:5' Untranslated Regions; D001426:Bacterial Proteins; D026901:Membrane Transport Proteins; D012333:RNA, Messenger; D038621:Regulatory Sequences, Ribonucleic Acid; D011392:Proline; D000251:Adenosine Triphosphatases; C093585:MgtA protein, bacteria; D008274:Magnesium
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