Affinage

NAGK

N-acetyl-D-glucosamine kinase · UniProt Q9UJ70

Length
344 aa
Mass
37.4 kDa
Annotated
2026-06-10
16 papers in source corpus 4 papers cited in narrative 4 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 5/5 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

NAGK (N-acetylglucosamine kinase) is a metabolic sugar kinase with dual roles in innate immunity and hexosamine salvage metabolism (PMID:36002575, PMID:34844667). In immune sensing, NAGK directly phosphorylates the C6 hydroxyl of the N-acetylmuramic acid moiety of muramyl dipeptide (MDP), generating 6-O-phospho-MDP; this phosphorylated species, not unmodified MDP, is the agonist that activates NOD2, and NAGK-deficient macrophages are completely unable to sense MDP (PMID:36002575). In parallel, NAGK phosphorylates free GlcNAc to feed UDP-GlcNAc pools through a hexosamine salvage pathway that becomes critical when de novo synthesis is limited by glutamine restriction, a dependence exploited by pancreatic ductal adenocarcinoma cells for tumor growth (PMID:34844667). This salvage-derived UDP-GlcNAc supply specifically supports Wnt signaling during vertebrate development, conserved across Xenopus, zebrafish, and Drosophila and required for Wnt-dependent intestinal enteroid growth (PMID:30904594). In the hypothalamus, NAGK supports transcription of Gnrh and Kiss1 and GnRH secretion, and its knockdown delays puberty onset in female mice (PMID:39488153).

Mechanistic history

Synthesis pass · year-by-year structured walk · 4 steps
  1. 2019 Medium

    Establishing whether NAGK has a developmental signaling role beyond housekeeping metabolism, this work showed that NAGK-dependent UDP-GlcNAc salvage selectively gates Wnt signaling.

    Evidence Kinase screen in Xenopus embryogenesis with pathway-specific reporters, genetic loss-of-function in zebrafish and Drosophila, and Wnt-dependent intestinal enteroid growth assay

    PMID:30904594

    Open questions at the time
    • Molecular link between UDP-GlcNAc levels and Wnt pathway specificity not resolved
    • Direct glycosylation target mediating Wnt dependence not identified
  2. 2021 High

    Defining the metabolic context where NAGK matters, this study showed that NAGK enables a hexosamine salvage route feeding UDP-GlcNAc when de novo synthesis is suppressed, supporting tumor growth.

    Evidence Isotope tracing/metabolomics with CRISPR/KO of NAGK and xenograft tumor growth in mice

    PMID:34844667

    Open questions at the time
    • Downstream glycoproteins dependent on salvage flux not enumerated
    • Generalizability beyond pancreatic ductal adenocarcinoma not established
  3. 2022 High

    Resolving the long-standing question of how cytosolic peptidoglycan fragments are recognized, this work identified NAGK as the kinase that converts MDP into the true NOD2 agonist.

    Evidence Forward genetic screen, in vitro phosphorylation assay, chemical characterization of 6-O-phospho-MDP, and NAGK knockout mouse macrophage functional assays

    PMID:36002575

    Open questions at the time
    • Structural basis of MDP recognition by NAGK not defined
    • How 6-O-phospho-MDP engages NOD2 mechanistically not detailed
  4. 2024 Medium

    Extending NAGK into neuroendocrine control, this study linked NAGK activity to hypothalamic GnRH/Kiss1 programs and puberty timing.

    Evidence siRNA knockdown in GT1-7 cells with RT-qPCR and GnRH secretion assays, plus ICV knockdown in mice with hormone measurement and immunofluorescence

    PMID:39488153

    Open questions at the time
    • Causal pathway from NAGK kinase activity to Gnrh/Kiss1 transcription not mapped
    • Relationship between observed β-catenin/Wnt changes and the GnRH phenotype unresolved

Open questions

Synthesis pass · forward-looking unresolved questions
  • Whether NAGK's metabolic salvage activity and its peptidoglycan-sensing activity are mechanistically coupled, and how a single sugar kinase coordinates these distinct outputs, remains open.
  • No unified structural/regulatory model linking the GlcNAc-salvage and MDP-phosphorylation activities
  • Tissue-specific control of which NAGK function dominates is uncharacterized

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0016740 transferase activity 2
Pathway
R-HSA-1430728 Metabolism 1 R-HSA-162582 Signal Transduction 1 R-HSA-168256 Immune System 1
Partners
NOD2

Evidence

Reading pass · 4 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2022 NAGK (N-acetylglucosamine kinase) directly phosphorylates the N-acetylmuramic acid moiety of muramyl dipeptide (MDP) at the hydroxyl group of its C6 position, yielding 6-O-phospho-MDP, which is the actual agonist for NOD2. Unmodified MDP does not activate NOD2; NAGK-phosphorylated MDP is required. Macrophages from NAGK-deficient mice are completely deficient in MDP sensing. Forward genetic screen, in vitro phosphorylation assay, NAGK knockout mice (macrophage functional assays), chemical characterization of phospho-MDP product Nature High 36002575
2021 NAGK mediates a hexosamine salvage pathway by phosphorylating free GlcNAc to feed UDP-GlcNAc pools when de novo hexosamine synthesis is suppressed by glutamine limitation. NAGK deletion from pancreatic ductal adenocarcinoma (PDA) cells impairs tumor growth in mice. Isotope tracing/metabolomics, NAGK genetic deletion (CRISPR/KO), xenograft mouse tumor growth assay eLife High 34844667
2019 Nagk and the UDP-GlcNAc glycosylation salvage pathway specifically regulate Wnt signaling during vertebrate development, without affecting Fgf, TGFβ, Notch, or Shh pathways. This role is evolutionarily conserved in Xenopus, zebrafish, and Drosophila. GlcNAc is essential for growth of intestinal enteroids, which are Wnt-dependent. Kinase screen in Xenopus embryogenesis, pathway-specific reporter assays, genetic loss-of-function in zebrafish and Drosophila, intestinal enteroid growth assay Mechanisms of development Medium 30904594
2024 NAGK knockdown in hypothalamic GT1-7 cells decreases transcription of Gnrh, Kiss1, Gpr54, Igf1, and Mapk14 mRNA and reduces GnRH secretion, while increasing β-catenin mRNA and apoptosis. In vivo, intracerebroventricular Nagk knockdown delays vaginal opening and reduces hypothalamic Gnrh and Kiss1 mRNA levels and serum E2 in female mice, establishing a role for NAGK in regulating puberty onset. siRNA knockdown in GT1-7 cells, RT-qPCR, GnRH secretion assay, ICV injection knockdown in mice, immunofluorescence, serum hormone measurement Theriogenology Medium 39488153

Source papers

Stage 0 corpus · 16 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2022 Phosphorylation of muramyl peptides by NAGK is required for NOD2 activation. Nature 60 36002575
2021 Glutamine deprivation triggers NAGK-dependent hexosamine salvage. eLife 43 34844667
2009 N-acetyl-L-glutamate kinase (NAGK) from oxygenic phototrophs: P(II) signal transduction across domains of life reveals novel insights in NAGK control. Journal of molecular biology 43 19409905
2018 The PII-NAGK-PipX-NtcA Regulatory Axis of Cyanobacteria: A Tale of Changing Partners, Allosteric Effectors and Non-covalent Interactions. Frontiers in molecular biosciences 41 30483512
2010 A novel signal transduction protein P(II) variant from Synechococcus elongatus PCC 7942 indicates a two-step process for NAGK-P(II) complex formation. Journal of molecular biology 35 20399792
2010 On the conservation of the slow conformational dynamics within the amino acid kinase family: NAGK the paradigm. PLoS computational biology 33 20386738
2011 Site-directed mutagenesis and feedback-resistant N-acetyl-L-glutamate kinase (NAGK) increase Corynebacterium crenatum L-arginine production. Amino acids 26 21901472
2019 Developmental regulation of Wnt signaling by Nagk and the UDP-GlcNAc salvage pathway. Mechanisms of development 18 30904594
2015 Energy Sensing versus 2-Oxoglutarate Dependent ATPase Switch in the Control of Synechococcus PII Interaction with Its Targets NAGK and PipX. PloS one 18 26317540
2013 From PII signaling to metabolite sensing: a novel 2-oxoglutarate sensor that details PII-NAGK complex formation. PloS one 18 24349456
2011 Site-directed mutagenesis studies on the L-arginine-binding sites of feedback inhibition in N-acetyl-L-glutamate kinase (NAGK) from Corynebacterium glutamicum. Current microbiology 17 22101454
2017 Evidence for PII with NAGK interaction that regulates Arg synthesis in the microalga Myrmecia incisa in response to nitrogen starvation. Scientific reports 12 29176648
2020 Implementation of the plasma MYCN/NAGK ratio to detect MYCN amplification in patients with neuroblastoma. Molecular oncology 6 32896084
2023 g-NK cells from umbilical cord blood are phenotypically and functionally different than g-NK cells from peripheral blood. Oncoimmunology 3 38126036
2026 The interaction between PII and NAGK regulates arginine biosynthesis in the green microalga Haematococcus pluvialis. Journal of phycology 0 41999177
2024 NAGK regulates the onset of puberty in female mice. Theriogenology 0 39488153

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