Quantitative Chemoproteomic Profiling of Protein Cross-Links Induced by Methylglyoxal

Methylglyoxal (MGO) is a highly reactive
metabolite mainly formed
as a byproduct of glycolysis. Elevated MGO has been considered as
a risk factor for several diseases including diabetes and neurodegeneration.
While MGO modifications on proteins were globally profiled, the cross-links
between proteins induced by MGO in proteomes are unexplored to date.
Here, we reported a quantitative chemoproteomic platform based on
mass shifts that enables identification of events of protein cross-links
induced by MGO in proteomes. A total of 66 cross-linked targets were
identified from the profiling experiments when cells were treated
with MGO, among which the components of functional complexes such
as spliceosomes and ribosomes were enriched. We found that inosine-5′-monophosphate
dehydrogenase 2 (IMPDH2) was homocross-linked by MGO and the active-site
Cys331 was critical for mediating the cross-link, which in turn affected
IMPDH2’s activity. Our study has provided new clues for the
functional impact in proteomes by MGO, and the methodology can be,
in principle, applied to profile protein cross-links induced by other
reactive metabolites.