Effects of colonization-associated gene yqiC on global transcriptome, cellular respiration, and oxidative stress in Salmonella Typhimurium

Abstract

Background yqiC is required for colonizing the Salmonella enterica serovar Typhimurium (S. Typhimurium) in human cells; however, how yqiC regulates nontyphoidal Salmonella (NTS) genes to influence bacteria–host interactions remains unclear. Methods The global transcriptomes of S. Typhimurium yqiC-deleted mutant (ΔyqiC) and its wild-type strain SL1344 after 2 h of in vitro infection with Caco-2 cells were obtained through RNA sequencing to conduct comparisons and identify major yqiC-regulated genes, particularly those involved in Salmonella pathogenicity islands (SPIs), ubiquinone and menaquinone biosynthesis, electron transportation chains (ETCs), and carbohydrate/energy metabolism. A Seahorse XFp Analyzer and assays of NADH/NAD+ and H2O2 were used to compare oxygen consumption and extracellular acidification, glycolysis parameters, adenosine triphosphate (ATP) generation, NADH/NAD+ ratios, and H2O2 production between ΔyqiC and SL1344. Results After S. Typhimurium interacts with Caco-2 cells, yqiC represses gene upregulation in aspartate carbamoyl transferase, type 1 fimbriae, and iron–sulfur assembly, and it is required for expressing ilvB operon, flagellin, tdcABCD, and dmsAB. Furthermore, yqiC is required for expressing mainly SPI-1 genes and specific SPI-4, SPI-5, and SPI-6 genes; however, it diversely regulates SPI-2 and SPI-3 gene expression. yqiC significantly contributes to menD expression in menaquinone biosynthesis. A Kyoto Encyclopedia of Genes and Genomes analysis revealed the extensive association of yqiC with carbohydrate and energy metabolism. yqiC contributes to ATP generation, and the analyzer results demonstrate that yqiC is required for maintaining cellular respiration and metabolic potential under energy stress and for achieving glycolysis, glycolytic capacity, and glycolytic reserve. yqiC is also required for expressing ndh, cydA, nuoE, and sdhB but suppresses cyoC upregulation in the ETC of aerobically and anaerobically grown S. Typhimurium; priming with Caco-2 cells caused a reversed regulation of yiqC toward upregulation in these ETC complex genes. Furthermore, yqiC is required for maintaining NADH/NAD+ redox status and H2O2 production. Conclusions Specific unreported genes that were considerably regulated by the colonization-associated gene yqiC in NTS were identified, and the key role and tentative mechanisms of yqiC in the extensive modulation of virulence factors, SPIs, ubiquinone and menaquinone biosynthesis, ETCs, glycolysis, and oxidative stress were discovered.

SalmonellaYqiC exerts its function through an oligomeric state

“…The last two proteins are the transcription termination factor Rho and the elongation factor Tuf1. These newly uncovered PPI of YqiC are consistent with recent functional characterizations of the protein that revealed roles in cellular respiration (Wang et al, 2016), oxidative stress (Fan et al, 2022), and UQ synthesis (Loiseau et al, 2017). Although neither Rho nor Tuf1 are directly related to energy production or virulence of Salmonella, YqiC might interact with these two proteins via similar structural motifs.…”

“…YqiC has also been associated with energy metabolism and ATP production in Salmonella (Fan et al, 2022). The YqiC knockout strain of Salmonella SL1344 displays significantly reduced ATP generation and oxygen consumption during cellular respiration.…”

“…However, the actual interacting sites between YqiC and SdhA/ SdhB await further investigation. Our recent collaborative study on the regulatory effects of YqiC (Fan et al, 2022) showed that the YqiC knockout strain of SL1344 modulates the expression of genes linked to iron-sulfur clusters and type I fimbriae assembly during early colonization of Caco-2 cells. A gene ontology enrichment analysis using the RNA-seq data from ΔyqiC and WT Salmonella SL1344 revealed significant upregulation of many genes related to iron-sulfur cluster binding and 4Fe-4S binding in the ΔyqiC strain.…”

“…The YqiC protein is responsible for bacterial motility, flagellar formation, and postinfectious induction of inflammatory cytokines in the human intestinal epithelium. Recent reports have also found that YqiC acts in cellular respiration, ATP production (Fan et al, 2022), menaquinone (MQ; Wang et al, 2016), and ubiquinone (UQ) synthesis (Loiseau et al, 2017). Biochemical characterizations of the YqiC protein have shown that it forms a homotrimer in vitro through C-terminal coiled-coil interactions (Carrica et al, 2011).…”

A Comprehensive Review on the Roles of Metals Mediating Insect–Microbial Pathogen Interactions

“…In addition, another trace metal, such as Mo, can affect bacterial physiology in several ways. For example, the concentration of Mo beyond the optimum requirement can lead to changes in bacterial metabolism, including a shift toward anaerobic respiration and altered expression of genes involved in energy metabolism [ 197 ]. There is ample room for further progress in determining how metals limit microbial growth and virulence, which is necessary for developing new strategies to combat microbial infections.…”