# Aberrant post-translational modifications characterize the hepatic proteome of methylmalonic acidemia

> **NIH NIH FI2** · NATIONAL HUMAN GENOME RESEARCH INST · 2020 · —

## Abstract

Project Summary
Organic acidemias (OAs), such as methylmalonic acidemia (MMA), are a group of inborn errors of metabolism
that typically arise from defects in the catabolism of amino- and fatty acids. OAs are difficult to treat and have
multisystemic manifestations, leading to increased morbidity and mortality. Accretion of acyl-CoA species is
postulated to cause intracellular toxicity. Here, we explore an alternative pathophysiological consequence of
impaired acyl-CoA metabolism: the accumulation of aberrant posttranslational modifications (PTMs) that modify
enzymes in critical intracellular pathways, especially during periods of increased stress. Using a mouse model
that recapitulates the hepatic mitochondriopathy of MMA (Mmut-/-;TgINS-MCK-Mut) as well as MMA patient liver
tissues, I surveyed PTMs in hepatic extracts with propionyl- and malonyl-lysine antibodies. I discovered
widespread hyper-acylation in the MMA mice and MMA patient tissue samples compared to their respective
control samples, but not in mice with Acsf3 deficiency, a disorder of acyl-CoA synthesis. Next, I prepared anti-
PTM antibody columns, purified hepatic extracts from MMA and control mice, and performed mass spectrometry
to characterize the PTM proteome. Excessive acylation of enzymes involved in glutathione, urea, arginine, lysine,
tryptophan, valine, isoleucine, methionine, threonine, and fatty acid metabolism were detected in the MMA mice
but not controls, and further validated mass spectrometry Cps1 hyperacylation via immunoprecipitation analysis
and Western blotting. In parallel, we generated, via nonenzymatic acylation reactions, PTM-modified BSA targets
for in vitro analyses. We purified, then assayed, SIRT1-7 deacylase activity using BSA-PTM standards to identify
the SIRT(s) that most efficiently remove MMA related PTMs. Because PTMs usually inhibit enzyme function, our
observations suggest that hyperacylation of key enzymes in pathways known to be dysregulated in MMA likely
contributes to altered metabolism and identifies a new set of targets for therapeutic intervention.

## Key facts

- **NIH application ID:** 10025497
- **Project number:** 1FI2GM137781-01
- **Recipient organization:** NATIONAL HUMAN GENOME RESEARCH INST
- **Principal Investigator:** PamelaSara Elbaz Head
- **Activity code:** FI2 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** —
- **Award type:** 1
- **Project period:** 2020-09-01 → 2023-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10025497

## Citation

> US National Institutes of Health, RePORTER application 10025497, Aberrant post-translational modifications characterize the hepatic proteome of methylmalonic acidemia (1FI2GM137781-01). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/10025497. Licensed CC0.

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