Isoaspartate-containing galanin in rat hypothalamus
Year: 2025
Type: article
Abstract: The isoaspartate residue is a spontaneous, time-dependent post-translational modification (PTM) of proteins and peptides, associated with in vivo protein aggregation and changes in molecule lifetime. While this is considered a slow modification impacting long lived proteins, surprisingly, we observed this PTM at high levels within the relatively short-lived neuropeptide galanin (Gal). The combination of liquid chromatography-trapped ion mobility mass spectrometry and protein Isoaspartyl methyltransferase assays demonstrated that 20 ± 2% of the mature Gal contain L-Isoaspartate residue in the hypothalamus of Rattus norvegicus. Aspartate in Gal isomerizes spontaneously under mildly acidic conditions within 48 h in vitro, much faster than previously assumed. Gal with the L-isoaspartate PTM significantly enhanced fibril formation. Transmission electron microscopy revealed differences in morphology of fibrils formed by D17Isoasparte Gal compared to the unmodified peptide. Observed characteristics of D17Isoasparte Gal suggest a potential mechanism for the development of in vivo Gal fibril deposits previously reported in the brain. The spontaneous formation of isoaspartate has been well-documented in long-lived proteins as an age-dependent post-translational modification. Here, by using liquid chromatography trapped ion mobility mass spectrometry, the authors report the short-lived neuropeptide galanin in the brain has around 20% in the isoaspartate form which enhances fibril formation.
Source: Communications Chemistry
Institution: University of Illinois Urbana-Champaign
Language: English
Subfield: Spectroscopy
Field: Chemistry
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,690
Awards: G2373864156, G2933868264, G3053539267, Isomerization in cell-to-cell signaling peptides: from discovery to function, High-Throughput 3D Multiscale Mass Spectrometry Imaging for Understanding Neurochemical Heterogeneity in Alzheimer's Disease, G600732768, G6288178167, The UIUC Neuroproteomics Center on Cell-Cell Signaling, G7944402577, G87441457
OpenAlex ID: W4408250362