Regulation of the yifK locus by multi-target small RNA GcvB in Salmonella
type: Dataset
description: GcvB is a conserved 200 nucleotide RNA that downregulates several genes involved in amino acid uptake or biosynthesis in bacteria. The physiological role of GcvB action is not entirely clear, but it is likely aimed at balancing of nutritional resources under fast growth conditions. GcvB inhibits translation of target messenger RNAs by pairing with sequences inside or upstream of ribosome binding sites. In the present study, characterization of a novel GcvB-regulated locus revealed some unique features in the mode of functioning of this regulatory RNA. We found that GcvB represses yifK - a highly conserved locus encoding a putative amino acid transporter - by targeting a translational enhancer element. Two ACA motifs within the target sequence are the main determinants of the enhancer activity. Replacing either of these motifs with random triplets caused up to a 10-fold decrease in yifK expression regardless of the GcvB allele (deleted or suitably modified to recognize the mutated target). It thus appears that GcvB effectiveness as a regulator results from countering the enhancer activity. When the enhancer is removed, GcvB action no longer constitutes a rate-limiting factor for yifK expression. Overall, this study is relevant not only to a better understanding of GcvB function but it also provides insight into an elusive aspect of the translation initiation process. Besides the GcvB control, the yifK locus is regulated at the transcriptional level by the leucine responsive regulator Lrp, and by HdfR (YifA) a poorly known transcriptional regulator, that appears to require the product of the adjacent, divergently oriented gene, yifE, for expression or activity. Transcription initiating at the yifK promoter extends into the adjacent argX-hisR-leuT-proM tRNA operon yielding an unusual primary transcript which both a messenger RNA and a tRNA precursor. This chimeric RNA si rapidly processed by RNAse E.
identifier: NNT: 2013PA112160
issued: 2026-05-06T04:18:42.845011
language: en
modified: 2026-05-06T04:18:42.845016
contact point: Organization
  fn: CCSD
keyword: aca
keyword: activateur-traductionnel
keyword: chip
keyword: dppa
keyword: gcvb
keyword: infoeu-reposemanticsdoctoralthesis
keyword: petit-arn
keyword: salmonella
keyword: sdvsalife-sciences-q-bioagricultural-sciences
keyword: small-rna
keyword: theses
keyword: translational-enhancer
keyword: yifk
landing page: https://theses.hal.science/tel-00954416

Regulation of the yifK locus by multi-target small RNA GcvB in Salmonella
type: Distribution
format: HTML
issued: 2026-05-06T04:18:42.853967
modified: 2026-05-06T04:18:42.831198
access URL: https://theses.hal.science/tel-00954416

test_moissonnage_selune
type: Agent