Structural basis of sugar recognition by SCFFBS2 ubiquitin ligase involved in NGLY1 deficiency

Abstract

The cytosolic peptide:N‐glycanase (PNGase) is involved in the quality control of N‐glycoproteins via the endoplasmic reticulum‐associated degradation (ERAD) pathway. Mutations in the gene encoding cytosolic PNGase (NGLY1 in humans) cause NGLY1 deficiency. Recent findings indicate that the F‐box protein FBS2 of the SCFFBS2 ubiquitin ligase complex can be a promising drug target for NGLY1 deficiency. Here, we determined the crystal structure of bovine FBS2 complexed with the adaptor protein SKP1 and a sugar ligand, Man3GlcNAc2, which corresponds to the core pentasaccharide of N‐glycan. Our crystallographic data together with NMR data revealed the structural basis of disparate sugar‐binding specificities in homologous FBS proteins and identified a potential druggable pocket for in silico docking studies. Our results provide a potential basis for the development of selective inhibitors against FBS2 in NGLY1 deficiency.