title: Translation inhibition of the Salmonella fliC gene by the fliC 5' untranslated region, fliC coding sequences, and FlgM.
abstract: The 5'-untranslated region (5'UTR) of the fliC flagellin gene of Salmonella contains sequences critical for efficient fliC mRNA translation coupled to assembly. In a previous study we used targeted mutagenesis of the 5' end of the fliC gene to isolate single base changes defective in fliC gene translation. This identified a predicted stem-loop structure, SL2, as an effector of normal fliC mRNA translation. A single base change (-38C:U) in the fliC 5'UTR resulted in a mutant that is defective in fliC mRNA translation and was chosen for this study. Motile (Mot+) revertants of the -38C:T mutant were isolated and characterized, yielding several unexpected results. Second-site suppressors that restored fliC translation and motility included mutations that disrupt a RNA duplex stem formed between RNA sequences in the fliC 5'UTR SL2 region (including a precise deletion of SL2) and bases early within the fliC-coding region. A stop codon mutation at position 80 of flgM also suppressed the -38C:T motility defect, while flgM mutants defective in anti-sigma28 activity had no effect on fliC translation. One remarkable mutation in the fliC 5'UTR (-15G:A) results in a translation defect by itself but, in combination with the -38C:U mutation, restores normal translation. These results suggests signals intrinsic to the fliC mRNA that have both positive and negative effects on fliC translation involving both RNA structure and interacting proteins.
authors.affiliation: Department of Microbiology, University of Utah, Salt Lake City, UT 84112, USA.
authors.forename: Valentina
authors.initials: V
authors.lastname: Rosu
authors.forename: Fabienne F V
authors.initials: FF
authors.lastname: Chevance
authors.forename: Joyce E
authors.initials: JE
authors.lastname: Karlinsey
authors.forename: Takanori
authors.initials: T
authors.lastname: Hirano
authors.forename: Kelly T
authors.initials: KT
authors.lastname: Hughes
mesh_terms: D020121:5' Untranslated Regions / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics* / Q000502:physiology; D001483:Base Sequence; D005407:Flagella; D005408:Flagellin / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D005786:Gene Expression Regulation; D008124:Locomotion; D008969:Molecular Sequence Data; D009154:Mutation; D009690:Nucleic Acid Conformation; D016366:Open Reading Frames; D014176:Protein Biosynthesis; D012329:RNA, Bacterial / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins; D012486:Salmonella typhimurium / Q000235:genetics* / Q000502:physiology
chemical_list: D020121:5' Untranslated Regions; D001426:Bacterial Proteins; D012329:RNA, Bacterial; D012097:Repressor Proteins; D005408:Flagellin; C071266:FlgM protein, Bacteria