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Bacterial antiviral defense pathways encode eukaryotic-like ubiquitination systems.
Lydia R Chambers1, Qiaozhen Ye2, Jiaxi Cai3
1Department of Chemistry and Biochemistry, University of California San Diego, La Jolla CA, USA.
Biorxiv : the Preprint Server for Biology
|October 9, 2023
Summary
Bacteria possess a complete ubiquitination pathway, previously thought to be exclusive to eukaryotes. This discovery reveals ancient origins of protein conjugation systems, impacting our understanding of cellular processes and evolution.
Area of Science:
- Molecular Biology
- Biochemistry
- Evolutionary Biology
Background:
- Ubiquitination is a vital post-translational modification regulating protein homeostasis, signaling, and immunity in eukaryotes.
- While bacteria have related proteins, a complete ubiquitination pathway was not known to exist in prokaryotes.
Approach:
- Structural analysis of bacterial E1:E2:Ubl complexes using X-ray crystallography.
- Biochemical assays to demonstrate Ubl conjugation to target proteins.
- Investigated the role of a deubiquitinase (DUB) in Ubl activation.
Key Points:
- Bacterial antiviral systems encode a complete ubiquitination pathway, including E1, E2, and Ubl proteins.
- Structural data reveals striking architectural and mechanistic parallels between bacterial and eukaryotic ubiquitination machinery.
- A bacterial DUB pre-processes the Ubl, enabling its conjugation by E1 and E2 enzymes.
Conclusions:
- Bacteria possess bona fide ubiquitination systems, challenging the eukaryotic-centric view of these pathways.
- The findings suggest that ubiquitination pathways may have originated in bacteria before eukaryotic evolution.
- This discovery opens new avenues for research into bacterial immunity and the evolution of cellular regulation.
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