Evolution, composition and functions of cullin E3 ubiquitin ligases in trypanosomes

TY - JOUR

T1 - Evolution, composition and functions of cullin E3 ubiquitin ligases in trypanosomes

AU - Canavate del Pino, Ricardo

AU - Zoltner, Martin

AU - Butterfield, Erin

AU - Field, Mark

N1 - © The Author(s) 2025

PY - 2025/12/18

Y1 - 2025/12/18

N2 - Post-translational modifications (PTMs) modulate protein functions, with ubiquitylation a preeminent example, and playing major roles in protein turnover. Ubiquitylation utilises a ligase enzyme cascade for conjugation of ubiquitin to client proteins, of which there are a large number in humans and lesser numbers in unicellular eukaryotes. The Cullin-RING ligases are amongst the most complex ligase subfamily and are present across the eukaryote lineage. We have reconstructed the evolution of cullin-RING E3 ubiquitin ligases across eukaryotes and experimentally determined the composition of six of seven cullin complexes in trypanosomatids. We find considerable diversity within cullins and reconstruct at least four ancestral pan-eukaryotic subfamilies. Furthermore, we identify expansions of cullin client adaptor protein families, novel client adaptors and demonstrate client specificity in trypanosomatids. We also find evidence for increasing complexity within client adaptors, suggesting ongoing expansion of adapter architecture. Finally, we show that turnover of ornithine decarboxylase (TbODC), an important target of the trypanocide eflornithine, is mediated by TbCul-A/CUL-1. These studies highlight lineage-specific aspects of cullin E3 ligases and their contributions towards eukaryotic complexity.

AB - Post-translational modifications (PTMs) modulate protein functions, with ubiquitylation a preeminent example, and playing major roles in protein turnover. Ubiquitylation utilises a ligase enzyme cascade for conjugation of ubiquitin to client proteins, of which there are a large number in humans and lesser numbers in unicellular eukaryotes. The Cullin-RING ligases are amongst the most complex ligase subfamily and are present across the eukaryote lineage. We have reconstructed the evolution of cullin-RING E3 ubiquitin ligases across eukaryotes and experimentally determined the composition of six of seven cullin complexes in trypanosomatids. We find considerable diversity within cullins and reconstruct at least four ancestral pan-eukaryotic subfamilies. Furthermore, we identify expansions of cullin client adaptor protein families, novel client adaptors and demonstrate client specificity in trypanosomatids. We also find evidence for increasing complexity within client adaptors, suggesting ongoing expansion of adapter architecture. Finally, we show that turnover of ornithine decarboxylase (TbODC), an important target of the trypanocide eflornithine, is mediated by TbCul-A/CUL-1. These studies highlight lineage-specific aspects of cullin E3 ligases and their contributions towards eukaryotic complexity.

KW - Cullin

KW - Ubiquitin

KW - E3 ligase

KW - Protein turnover

KW - Evolution

KW - Affinity isolation

KW - Cryomilling

KW - Eflornithine

KW - Ornithine decarboxylase

KW - Trypanosoma

KW - Proteomics

U2 - 10.1038/S41598-025-32077-9

DO - 10.1038/S41598-025-32077-9

M3 - Article

SN - 2045-2322

VL - 16

JO - Scientific Reports

JF - Scientific Reports

M1 - 2285

ER -