Affinage · Plasmodium

NSUN2

PF3D7_1111000 · RNA cytosine C(5)-methyltransferase NSUN2

Annotated
2026-09-08
6 papers in source corpus 1 papers cited in narrative 4 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

NSUN2 (PF3D7_1111000) is the major mRNA m5C (5-methylcytosine) methyltransferase of malaria parasites and is required for sexual differentiation (PMID:35210361). Genetic knockout of the P. yoelii ortholog abolishes m5C deposition across gametocytogenesis-associated transcripts, and complementation restores both the modification and the phenotype, establishing NSUN2 as the enzyme responsible for mRNA m5C (PMID:35210361). Mechanistically, NSUN2-deposited m5C confers stability on target mRNAs: loss of NSUN2 reduces the abundance of m5C-modified gametocytogenesis transcripts, linking the modification to transcript stabilization (PMID:35210361). This activity is coupled to the parasite life cycle, as m5C is strikingly enriched in the gametocyte transcriptome of both P. yoelii and P. falciparum relative to asexual stages, and NSUN2 loss impairs gametocyte production in a manner fully reversible by restoring expression (PMID:35210361). Beyond its identification as the m5C writer and its role in transcript stability and sexual commitment, no structural, catalytic-mechanistic, or interaction detail for NSUN2 has been characterized in the available corpus.

Mechanistic history

Synthesis pass · year-by-year structured walk · 4 steps
  1. 2022 High

    It was unknown which enzyme deposits mRNA m5C in malaria parasites; identifying NSUN2 as the writer defined the molecular basis of this modification.

    Evidence Bisulfite-seq m5C profiling with genetic knockout of pynsun2 in P. yoelii and complementation rescue

    PMID:35210361

    Open questions at the time
    • No direct biochemical demonstration of catalytic activity or substrate-sequence specificity in vitro
    • Structural basis and catalytic residues not defined
    • Interaction partners or cofactors not characterized
  2. 2022 High

    The functional consequence of NSUN2-deposited m5C was unknown; loss-of-function linked the modification to mRNA stability.

    Evidence pynsun2 knockout with transcriptome-wide m5C profiling, transcript abundance measurement, and complementation rescue

    PMID:35210361

    Open questions at the time
    • Mechanism by which m5C stabilizes transcripts (e.g. reader proteins) not identified
    • Direct versus indirect effects on transcript abundance not fully separated
  3. 2022 High

    Whether m5C deposition has a developmental role was unknown; NSUN2 loss showed it is required for gametocyte production.

    Evidence Genetic knockout of pynsun2 with gametocyte quantification and complementation rescue in P. yoelii

    PMID:35210361

    Open questions at the time
    • Specific gametocytogenesis transcripts whose stabilization drives the phenotype not pinpointed
    • Whether the P. falciparum ortholog is likewise required for gametocytogenesis not functionally tested
  4. 2022 Medium

    It was unclear whether m5C is life-cycle-stage-regulated; profiling revealed enrichment in the gametocyte transcriptome.

    Evidence Single-nucleotide resolution m5C profiling across asexual and gametocyte stages of P. yoelii and P. falciparum

    PMID:35210361

    Open questions at the time
    • No functional perturbation tied to this stage-specific observation
    • Whether NSUN2 expression/activity itself is upregulated in gametocytes not directly measured

Open questions

Synthesis pass · forward-looking unresolved questions
  • The catalytic mechanism, substrate recognition, structural organization, and m5C-reader partners of NSUN2 remain undefined.
  • No in vitro reconstitution of methyltransferase activity
  • No structural model or defined catalytic residues
  • No identified m5C reader proteins mediating transcript stabilization

Mechanism profile

Synthesis pass · controlled-vocabulary classification
No controlled-vocabulary terms were assigned to this entry.

Evidence

Reading pass · 4 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2022 Plasmodium NSUN2 (PF3D7_1111000 ortholog) is a major mRNA m5C (5-methylcytosine) methyltransferase in malaria parasites. Knockout of P. yoelii nsun2 caused marked reductions in m5C modification across gametocytogenesis-associated transcripts, demonstrating NSUN2 is required for mRNA m5C deposition. Bisulfite-sequencing-based m5C transcriptome profiling; genetic knockout of pynsun2 in P. yoelii followed by m5C quantification; complementation (rescue) of the knockout restoring both m5C modification and gametocyte production phenotype. Proceedings of the National Academy of Sciences of the United States of America High 35210361
2022 NSUN2-mediated m5C modification confers stability to Plasmodium mRNA transcripts. Loss of NSUN2 correlated with reduced abundance of m5C-modified gametocytogenesis-associated mRNAs, establishing that m5C deposition by NSUN2 stabilizes these transcripts. Knockout of pynsun2 combined with transcriptome-wide m5C profiling and transcript abundance measurement; genetic complementation rescued transcript stability and m5C levels. Proceedings of the National Academy of Sciences of the United States of America High 35210361
2022 NSUN2-mediated mRNA m5C modification is required for gametocyte production (sexual differentiation). Knockout of pynsun2 in P. yoelii caused impaired gametocyte production, which was fully rescued by restoring nsun2 expression. Genetic knockout of pynsun2; gametocyte production quantification; complementation rescue of knockout parasites. Proceedings of the National Academy of Sciences of the United States of America High 35210361
2022 The abundance of m5C mRNA modifications is strikingly enhanced in gametocyte transcriptomes compared to asexual stages in both P. yoelii and P. falciparum, consistent with a stage-specific upregulation of NSUN2 methyltransferase activity. Single-nucleotide resolution m5C transcriptome profiling across asexual and gametocyte stages of P. yoelii and P. falciparum. Proceedings of the National Academy of Sciences of the United States of America Medium 35210361

Source papers

Stage 0 corpus · 6 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2000 A simple RNA analysis method shows var and rif multigene family expression patterns in Plasmodium falciparum. Molecular and biochemical parasitology 234 10693754
1968 DNA, RNA , and protein synthesis in erythrocytic forms of Plasmodium knowlesi. The American journal of tropical medicine and hygiene 56 4971014
1994 The ribosomal RNA genes of Plasmodium. Advances in parasitology 46 7976752
2022 5-methylcytosine modification by Plasmodium NSUN2 stabilizes mRNA and mediates the development of gametocytes. Proceedings of the National Academy of Sciences of the United States of America 30 35210361
2025 m5C methylation of mitochondrial RNA and non-coding RNA by NSUN3 is associated with variant gene expression and asexual blood-stage development in Plasmodium falciparum. Parasites & vectors 3 40148982
2025 A tale of two parasites: a glimpse into the RNA methylome of patient-derived Plasmodium falciparum and Plasmodium vivax isolates. Malaria journal 1 40316999