tRNAPro-mediated downregulation of elongation factor P is required for mgtCBR expression during Salmonella infection

Daesil Nam, Eunna Choi, Dongwoo Shin, Eun Jin Lee

Research output: Contribution to journalArticlepeer-review

16 Citations (Scopus)


Bacterial ribosome requires elongation factor P to translate fragments harbouring consecutive proline codons. Given the abundance of ORFs with potential EF-P regulated sites, EF-P was assumed to be constitutively expressed. Here, we report that the intracellular pathogen Salmonella enterica serovar Typhimurium decreases efp mRNA levels during course of infection. We determined that the decrease in efp mRNA is triggered by low levels of charged tRNAPro, a condition that Salmonella experiences when inside a macrophage phagosome. Surprisingly, downregulation of EF-P selectively promotes expression of the virulence mgtC gene and contributes to Salmonella's ability to survive inside macrophages. The decrease in EF-P levels induces ribosome stalling at the consecutive proline codons of the mgtP open reading frame in the mgtCBR leader RNA, and thus allows formation of a stem-loop structure promoting transcription of the mgtC gene. The substitution of proline codons in the mgtP gene eliminates EF-P-mediated mgtC expression and thus Salmonella's survival inside macrophages. Our findings indicate that Salmonella benefits virulence genes by decreasing EF-P levels and inducing the stringent response inside host.

Original languageEnglish
Pages (from-to)221-232
Number of pages12
JournalMolecular Microbiology
Issue number2
Publication statusPublished - 2016 Oct 1
Externally publishedYes

ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology


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