The content explores the substrate recognition mechanism of the E3 ubiquitin ligase Parkin. Key highlights:
Untagged, full-length Parkin activated by phosphorylation can ubiquitinate a variety of proteins, but exhibits a strong preference for the mitochondrial GTPase Miro1 in a mix of substrates.
Despite the low affinity of the interaction, the authors were able to capture a Parkin-Miro1 complex using chemical crosslinking. This allowed them to identify a conserved substrate targeting region (STR) within the linker domain of Parkin that is crucial for binding to Miro1.
Computational modeling using AlphaFold predicted the STR region in Parkin to interact with a hydrophobic pocket in the EF1 domain of Miro1. Disrupting this interaction, either by mutating key residues or by competing with a synthetic STR-containing peptide, compromised Miro1 ubiquitination by Parkin.
The authors propose that the STR-mediated Parkin-Miro1 interaction allows Parkin to be pre-positioned at the mitochondrial membrane, primed for rapid activation and ubiquitination of Miro1 upon mitochondrial damage, which is an important step in the mitophagy process.
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by Koszela,J., ... at www.biorxiv.org 06-03-2024
https://www.biorxiv.org/content/10.1101/2024.06.03.597144v1Deeper Inquiries