M Karpiyevich3; S Adjalley2; D Ascher4; G J van der Heyden van Noor1; B Mason3; H Laman3; H Ovaa1; M Lee2; K Artavanis-Tsakonas3;
1 Leiden University Medical Centre, Netherlands; 2 The Wellcome Sanger Institute, UK; 3 University of Cambridge, UK; 4 University of Melbourne, Australia
DiscussionNedd8 is a conserved ubiquitin-like protein that is conjugated to protein substrates, resulting in a post-translational modification referred to as neddylation. As a regulator of numerous cellular processes, protein neddylation is essential in a wide range of organisms including mammals, plants, and fission yeast. Nedd8 is a dynamic modification that is attached to substrates via a three-step enzymatic cascade mediated by the E1, E2, and E3 enzymes and can be removed by deneddylases. Orthologs of Nedd8, Nedd8 E1, E2, and E3 enzymes, as well as two cullin substrates with conserved neddylation sites, were identified in Plasmodium using bioinformatics approaches. However, key deneddylating enzymes NeddP1, CSN5/COP9 signalosome, UCHL1, and USP21 were not found, indicating that the Nedd8 pathway may be regulated differently in Plasmodium and its human host. We have identified a panel of potential P. falciparum deneddylases through the use of activity based probes and proteomic analysis and assessed their enzymatic activity. We further characterised the molecular determinants underlying the Nedd8 specificity of P. falciparum UCH37 and elucidated its contribution to parasite viability.