Skip to content
DraconiticResearch
Search Sources API
203,234 studies31 sourcesUpdated 10 min ago
Peer-reviewedCC BYPLOS Pathogens

Modulation of riboflavin biosynthesis enzymes in non-typhoidal Salmonella isolates differentially impacts human MAIT cell activation

  • Leia Vainman1
  • Corinna A. Kulicke2
  • Nurudeen Oketade3
  • Noa Bossel Ben-Moshe1
  • Camilla Ciolli-Mattioli1,4,5
  • Aryeh Solomon1
  • Jay C. D. Hinton6
  • Karen M. Dobos3
  • David M. Lewinsohn2,7
  • Shelly Hen-Avivi1
  • Roi Avraham1
7 affiliations
  1. 1Department of Immunology and Regenerative Biology, Weizmann Institute of Science, Rehovot, Israel
  2. 2Division of Pulmonary, Allergy, and Critical Care Medicine, Oregon Health and Science University, Portland, Oregon, United States of America
  3. 3Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, United States of America
  4. 4Helmholtz Institute for RNA-based Infection Research (HIRI), Helmholtz Centre for Infection Research (HZI), Würzburg, Germany
  5. 5Faculty of Medicine, University of Würzburg, Würzburg, Germany
  6. 6Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, United Kingdom
  7. 7VA Portland Health Care System, Portland, Oregon, United States of America
Read full textPDFDOICite

Abstract

Invasive non-typhoidal Salmonella (iNTS) sequence type 313 (ST313) isolates have emerged in sub-Saharan Africa, with a high incidence of multidrug resistance, enhanced intracellular persistence, increased dissemination and immune evasion. ST313 isolate D23580 was shown to avoid activation of mucosal-associated invariant T (MAIT) cells compared with a genetically similar, non-invasive Salmonella Typhimurium (S.Tm) 4/74 strain, but the mechanism remains unclear. Here, we studied immune responses to infection with typhoidal strains and ST313 isolates using comparative transcriptomic profiling of human peripheral blood mononuclear cells (PBMCs). MAIT cells responded to typhoidal strains but not to D23580. To uncover underlying mechanisms, we engineered an inducible CRISPRi system targeting riboflavin biosynthesis enzymes (rib), which process MAIT ligands, in D23580 and 4/74 strains. Several rib hypomorphs exhibited prolonged lag time in minimal media, which was more pronounced in D23580 than in 4/74. In PBMC infection, knockdown of lumazine synthase (RibH) and riboflavin synthase (RibE) resulted in contrasting MAIT cell activation phenotypes. RibH knockdown restored MAIT cell activation in D23580 but did not affect activation in 4/74. Conversely, RibE knockdown diminished MAIT cell activation by 4/74 but had no impact on MAIT cell activation by D23580. Metabolomic analysis revealed accumulation of the biosynthetic intermediate DMRL in RibE knockdown and a differential impact on riboflavin biosynthesis end products between D23580 and 4/74 RibH knockdown, suggesting altered pathway flux between the strains. Our results indicate RibH and RibE as pivotal nodes for strain-specific MAIT-activation during Salmonella infection of human PBMCs, illustrating teir central role in the complex interplay between bacterial metabolism and host immunity. Author summary: Invasive non-typhoidal Salmonella (iNTS) is a major cause of bloodstream infections in sub-Saharan Africa, where it causes severe disease and high mortality. A particular lineage, sequence type 313 (ST313), has evolved the ability to evade immune responses, including activation of mucosal-associated invariant T (MAIT) cells, an important component of the early antibacterial immune response. MAIT cells recognize small molecules generated during bacterial riboflavin (vitamin B2) biosynthesis, but how ST313 avoids this recognition has remained unclear. Here, we compared immune responses to invasive and non-invasive Salmonella strains and used an inducible CRISPR interference system to selectively reduce expression of riboflavin biosynthesis genes. We found that two enzymes, RibH and RibE, have distinct and strain-specific effects on MAIT cell activation. Reducing RibH expression restored MAIT cell activation in the invasive ST313 strain, whereas reducing RibE impaired MAIT cell activation in the non-invasive strain. Metabolomic analyses showed that these genetic perturbations altered riboflavin pathway intermediates differently in each strain, revealing unexpected differences in metabolic flux. Our findings demonstrate that changes in bacterial vitamin B2 metabolism can profoundly influence immune recognition, providing new insight into how invasive Salmonella adapts to evade host immunity.

Related

  1. Type I and III interferons differentially encode inflammatory gene activation through threshold control of ISGF3 dynamics
    H. Dubon Martinez, R. Chettiyar, M. McAuley +1
    bioRxivPreprintAll rights reservedFull textMolecular biology & gene regulationbioRxiv
  2. Allosteric modulation of YTHDFs by ellagic acid suppresses triple-negative breast cancer via non-canonical activation of the HIF-1α pathway
    Jianheng Zhou, Yuyuan Li, Xuetao Chen +9
    Cell Reports MedicinePeer-reviewedCC BY-NC-ND 4.0Full textMolecular biology & gene regulationPMC
  3. Molecular insights into GPR55 modulation reveal an atypical activation mechanism and glycosylation-dependent efficacy regulation
    Tobias Claff, Chamalee Demalgiriya-Gamage, Andhika B. Mahardhika +12
    Nature CommunicationsPeer-reviewedCC BY-NC-ND 4.0Full textMolecular biology & gene regulationCrossrefEurope PMC
  4. Biochemical and Binding Characterization of a Riboflavin Analogue Tethered to Biotin
    S. Marincean, S. R. Smith, T. Branscum +2
    bioRxivPreprintCC BYFull textMolecular biology & gene regulationbioRxiv
  5. A thioester-thiol exchange reaction in Salmonella Invasion acyl carrier protein transfers the 4PP-bound acyl chain to a distal cysteine
    R. Prem, G. Garima, D. Sadhukhan +1
    bioRxivPreprintAll rights reservedFull textGeneral biochemistrybioRxiv

Cite

BibTeXRIS
BibTeX
@article{vainman2026modulation,
  title = {{Modulation of riboflavin biosynthesis enzymes in non-typhoidal Salmonella isolates differentially impacts human MAIT cell activation}},
  author = {Leia Vainman and Corinna A. Kulicke and Nurudeen Oketade and Noa Bossel Ben-Moshe and Camilla Ciolli-Mattioli and Aryeh Solomon and Jay C. D. Hinton and Karen M. Dobos and David M. Lewinsohn and Shelly Hen-Avivi and Roi Avraham},
  journal = {PLOS Pathogens},
  year = {2026},
  month = nov,
  doi = {10.1371/journal.ppat.1014715},
  url = {https://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1014715},
  note = {CC BY},
}
RIS
TY  - JOUR
TI  - Modulation of riboflavin biosynthesis enzymes in non-typhoidal Salmonella isolates differentially impacts human MAIT cell activation
AU  - Leia Vainman
AU  - Corinna A. Kulicke
AU  - Nurudeen Oketade
AU  - Noa Bossel Ben-Moshe
AU  - Camilla Ciolli-Mattioli
AU  - Aryeh Solomon
AU  - Jay C. D. Hinton
AU  - Karen M. Dobos
AU  - David M. Lewinsohn
AU  - Shelly Hen-Avivi
AU  - Roi Avraham
PY  - 2026
DA  - 2026/11/01
JO  - PLOS Pathogens
DO  - 10.1371/journal.ppat.1014715
UR  - https://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1014715
AB  - Invasive non-typhoidal Salmonella (iNTS) sequence type 313 (ST313) isolates have emerged in sub-Saharan Africa, with a high incidence of multidrug resistance, enhanced intracellular persistence, increased dissemination and immune evasion. ST313 isolate D23580 was shown to avoid activation of mucosal-associated invariant T (MAIT) cells compared with a genetically similar, non-invasive Salmonella Typhimurium (S.Tm) 4/74 strain, but the mechanism remains unclear. Here, we studied immune responses to infection with typhoidal strains and ST313 isolates using comparative transcriptomic profiling of human peripheral blood mononuclear cells (PBMCs). MAIT cells responded to typhoidal strains but not to D23580. To uncover underlying mechanisms, we engineered an inducible CRISPRi system targeting riboflavin biosynthesis enzymes (rib), which process MAIT ligands, in D23580 and 4/74 strains. Several rib hypomorphs exhibited prolonged lag time in minimal media, which was more pronounced in D23580 than in 4/74. In PBMC infection, knockdown of lumazine synthase (RibH) and riboflavin synthase (RibE) resulted in contrasting MAIT cell activation phenotypes. RibH knockdown restored MAIT cell activation in D23580 but did not affect activation in 4/74. Conversely, RibE knockdown diminished MAIT cell activation by 4/74 but had no impact on MAIT cell activation by D23580. Metabolomic analysis revealed accumulation of the biosynthetic intermediate DMRL in RibE knockdown and a differential impact on riboflavin biosynthesis end products between D23580 and 4/74 RibH knockdown, suggesting altered pathway flux between the strains. Our results indicate RibH and RibE as pivotal nodes for strain-specific MAIT-activation during Salmonella infection of human PBMCs, illustrating teir central role in the complex interplay between bacterial metabolism and host immunity. Author summary: Invasive non-typhoidal Salmonella (iNTS) is a major cause of bloodstream infections in sub-Saharan Africa, where it causes severe disease and high mortality. A particular lineage, sequence type 313 (ST313), has evolved the ability to evade immune responses, including activation of mucosal-associated invariant T (MAIT) cells, an important component of the early antibacterial immune response. MAIT cells recognize small molecules generated during bacterial riboflavin (vitamin B2) biosynthesis, but how ST313 avoids this recognition has remained unclear. Here, we compared immune responses to invasive and non-invasive Salmonella strains and used an inducible CRISPR interference system to selectively reduce expression of riboflavin biosynthesis genes. We found that two enzymes, RibH and RibE, have distinct and strain-specific effects on MAIT cell activation. Reducing RibH expression restored MAIT cell activation in the invasive ST313 strain, whereas reducing RibE impaired MAIT cell activation in the non-invasive strain. Metabolomic analyses showed that these genetic perturbations altered riboflavin pathway intermediates differently in each strain, revealing unexpected differences in metabolic flux. Our findings demonstrate that changes in bacterial vitamin B2 metabolism can profoundly influence immune recognition, providing new insight into how invasive Salmonella adapts to evade host immunity.
SN  - 1553-7374
SN  - 1553-7366
ER  -