Open AccessRplI interacts with 5’ UTR of exsA to repress its translation and type III secretion system in Pseudomonas aeruginosa
Author(s) -
Dan Wang,
Xinxin Zhang,
Liwen Yin,
Qi Liu,
Zixiang Yu,
Congjuan Xu,
Zhenzhen Ma,
Yushan Xia,
Jing Shi,
Yuehua Gong,
Fang Bai,
Zhihui Cheng,
Weihui Wu,
Jinzhong Lin,
Yongxin Jin
Publication year - 2022
Publication title -
plos pathogens
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.719
H-Index - 206
eISSN - 1553-7374
pISSN - 1553-7366
DOI - 10.1371/journal.ppat.1010170
Subject(s) - biology , repressor , gene knockdown , microbiology and biotechnology , type three secretion system , untranslated region , ribosomal protein , gene , mutant , ribosome , gene expression , messenger rna , genetics , rna
Pseudomonas aeruginosa is an important opportunistic pathogen capable of causing variety of infections in humans. The type III secretion system (T3SS) is a critical virulence determinant of P . aeruginosa in the host infections. Expression of the T3SS is regulated by ExsA, a master regulator that activates the expression of all known T3SS genes. Expression of the exsA gene is controlled at both transcriptional and posttranscriptional levels. Here, we screened a P . aeruginosa transposon (Tn5) insertional mutant library and found rplI , a gene coding for the ribosomal large subunit protein L9, to be a repressor for the T3SS gene expression. Combining real-time quantitative PCR (qPCR), western blotting and lacZ fusion assays, we show that RplI controls the expression of exsA at the posttranscriptional level. Further genetic experiments demonstrated that RplI mediated control of the exsA translation involves 5’ untranslated region (5’ UTR). A ribosome immunoprecipitation assay and qPCR revealed higher amounts of a 24 nt fragment from exsA mRNA being associated with ribosomes in the Δ rplI mutant. An interaction between RplI and exsA mRNA harboring its 24 nt, but not 12 nt, 5’ UTR was confirmed by RNA Gel Mobility Shift and Microscale Thermophoresis assays. Overall, this study identifies the ribosomal large subunit protein L9 as a novel T3SS repressor that inhibits ExsA translation in P . aeruginosa .