MnmE, a Central tRNA-Modifying GTPase, Is Essential for the Growth, Pathogenicity, and Arginine Metabolism of Streptococcus suis Serotype 2

Abstract

Streptococcus suis is an important pathogen in pigs and can also cause severe infections in humans. However, little is known about proteins associated with cell growth and pathogenicity of S. suis . In this study, a guanosine triphosphatase (GTPase) MnmE homolog was identified in a Chinese isolate (SC19) that drives a tRNA modification reaction. A mnmE deletion strain (Δ mnmE ) and a complementation strain (CΔ mnmE ) were constructed to systematically decode the characteristics and functions of MnmE both in vitro and in vivo studies via proteomic analysis. Phenotypic analysis revealed that the Δ mnmE strain displayed deficient growth, attenuated pathogenicity, and perturbation of the arginine metabolic pathway mediated by the arginine deiminase system (ADS). Consistently, tandem mass tag -based quantitative proteomics analysis confirmed that 365 proteins were differentially expressed (174 up- and 191 down-regulated) between strains Δ mnmE and SC19. Many proteins associated with DNA replication, cell division, and virulence were down-regulated. Particularly, the core enzymes of the ADS were significantly down-regulated in strain Δ mnmE . These data also provide putative molecular mechanisms for MnmE in cell growth and survival in an acidic environment. Therefore, we propose that MnmE, by its function as a central tRNA-modifying GTPase, is essential for cell growth, pathogenicity, as well as arginine metabolism of S. suis .

One‐carbon metabolism, folate, zinc and translation

“…This implies that the MnmEG complex must discriminate against a variety of uridine residues located within RNA loops. This discrimination is performed by the potassium‐dependent GTPase activity of subunit E of the complex (Fislage et al , 2016; Shalaeva et al , 2018; Boel et al , 2019; Danchin and Nikel, 2019; Gao et al , 2019). Remarkably, this subunit also regulates the activity of the H 4 F‐related enzyme, poly‐γ‐glutamyl H 2 F/H 4 F synthase FolC, discussed at the beginning of this article.…”

“…However, while the modifications were likely important for proper integration of metabolism, they did not usually have a significant effect on the growth rate of E. coli strains in standard growth conditions. In contrast, when the host strain was deficient in the synthesis of polyamines, deletion of the mnmE or mnmG gene resulted in complete inhibition of growth unless the medium contained polyamines (Rodionova et al , 2018; Shalaeva et al , 2018; Gao et al , 2019; Keller et al , 2019).…”

RNA Modifications in Pathogenic Bacteria: Impact on Host Adaptation and Virulence

“…The modified nucleotide mnm 5 s 2 U34 is also important for virulence in other bacteria. In Streptococcus species, Gram-positive bacteria responsible for a wide range of infections from skin infection to sepsis, GidA/MnmE modification enzymes are essential for acid stress and high temperature adaptation [160], for pathogenicity [161], reduced ability of adhesion and invasion in epithelial cells, and increased sensitivity to phagocytosis [162]. Transposon mutagenesis in gidA gene is leading to sensitivity to acidic conditions also in Cronobacter sakazakii, an opportunist pathogen causing neonatal meningitis, enterocolitis, septicemia, bloody diarrhea, and brain abscesses, decreasing its ability to growth in host digestive system [163].…”

Proteomic and Metabolomic Analyses Provide Insights into the Mechanism on Arginine Metabolism Regulated by tRNA Modification Enzymes GidA and MnmE of Streptococcus suis

“…The bacterial strains and plasmids used in this study are listed in Table 1, strain SC19 was isolated from a diseased pig during an epidemic outbreak in 2005 in Sichuan, China (Li et al, 2009). The mnmE deletion mutant of SC19 (DmnmE) obtained from our previous research were also used in this study (Gao et al, 2019). The SS2 were grown in Todd-Hewitt broth (THB; Oxoid, Basingstoke, England) or on THB agar (THA; Oxoid, Basingstoke, England) plates supplemented with 5% sheep blood (Maojie, Nanjing, China) at 37°C.…”

“…GidA and MnmE, two important tRNA modification enzymes, are involved in the addition of the cmnm group in the position 5 of the wobble uridine 34 of tRNAs that read codons ending with A or G (Yim et al, 2006;Shippy and Fadl, 2015;Gao et al, 2019). Correspondingly, the orthologs of GidA and MnmE are called MTO1 and MSS1/GTPBP3 in yeast and human respectively (Zhu et al, 2015).…”