PXD078525

PXD078525 is an original dataset announced via ProteomeXchange.

Title	Dynamic N-terminal regulation couples GNMT folate feedback to methyl-donor homeostasis
Description	One carbon metabolism supports essential cellular functions, including biomolecule methylation, nucleotide and polyamine synthesis, and redox homeostasis. These processes depend on maintenance of S-adeno-sylmethionine (SAM) homeostasis. Although all methyltransferases consume SAM, only a subset appears to regulate intracellular SAM levels, and public datasets suggest that expression of these SAM-modulating enzymes are highly tissue-restricted. Among them, glycine N-methyltransferase (GNMT) is highly enriched in liver, declines with cancer and aging, and has been linked to disrupted liver homeostasis. However, the mechanisms connecting GNMT dysregulation to these phenotypes remain unclear. Previous in vitro studies showed that GNMT can be inhibited by 5-methyltetrahydrofolate (5mTHF), suggesting a negative-feedback mechanism, but the biological significance of this regulation is unresolved. Here, we identify the GNMT N-terminal tail, and specifically phosphorylation at serine 9 (S9ph), as a regulatory element linking folate-de-pendent feedback inhibition to SAM homeostasis. Structural and biochemical analyses showed that the N-terminal tail is required for efficient catalytic turnover and 5mTHF binding. Phosphoproteomic analysis fur-ther showed that S9ph is abundant in mouse liver GNMT and enriched in aged mice. Consistent with loss of folate-dependent negative feedback, both distal N-terminal truncation (residues 1–8) and a phosphomi-metic S9E substitution abolished 5mTHF binding while preserving catalytic activity. In hepatocyte cell lines lacking endogenous GNMT, truncated GNMT, but not full-length GNMT, depleted SAM, increased SAH, disrupted protein methylation, impaired growth, and induced transcriptional responses consistent with me-thyl-donor stress. Together, these findings identify the GNMT N-terminus as a tunable phosphoregulatory module that restrains enzyme activity and preserves methylation capacity.
HostingRepository	PRIDE
AnnounceDate	2026-08-18
AnnouncementXML	Submission_2026-08-18_06:45:23.259.xml
DigitalObjectIdentifier
ReviewLevel	Peer-reviewed dataset
DatasetOrigin	Original dataset
RepositorySupport	Unsupported dataset by repository
PrimarySubmitter	Simone Sidoli
SpeciesList	scientific name: Mus musculus (Mouse); NCBI TaxID: NEWT:10090;
ModificationList	No PTMs are included in the dataset
Instrument	Orbitrap Fusion Lumos; timsTOF HT

Revision	Datetime	Status	ChangeLog Entry
0	2026-05-18 19:06:06	ID requested
⏵ 1	2026-08-18 06:45:23	announced

Dataset with its publication pending

submitter keyword: SAM, Folate,One Carbon Metabolism, Methylation, GNMT, Methionine

Simone Sidoli
contact affiliation	Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461, United States
contact email	simone.sidoli@einsteinmed.edu
lab head
Simone Sidoli
contact affiliation	Albert Einstein College of Medicine
contact email	simone.sidoli@gmail.com
dataset submitter

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PRIDE project URI

• PRIDE
  1. PXD078525
     1. Label: PRIDE project
     2. Name: Dynamic N-terminal regulation couples GNMT folate feedback to methyl-donor homeostasis