Cellular targets and lysine selectivity of the HERC5 ISG15 ligase
Xu Zhao,
Jessica M. Perez,
Peter A. Faull,
Catherine Chan,
Femke W. Munting,
Larissa A. Canadeo,
Can Cenik,
Jon M. Huibregtse
Affiliations
Xu Zhao
Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
Jessica M. Perez
Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
Peter A. Faull
Biological Mass Spectrometry Facility, Center for Biomedical Research Support, University of Texas at Austin, Austin, TX 78712, USA
Catherine Chan
Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
Femke W. Munting
Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
Larissa A. Canadeo
Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
Can Cenik
Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
Jon M. Huibregtse
Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA; John Ring LaMontagne Center for Infectious Disease, University of Texas at Austin, Austin, TX 78712, USA; Corresponding author
Summary: ISG15 is a type I interferon-induced ubiquitin-like modifier that functions in innate immune responses. The major human ISG15 ligase is hHERC5, a ribosome-associated HECT E3 that broadly ISGylates proteins cotranslationally. Here, we characterized the hHERC5-dependent ISGylome and identified over 2,000 modified lysines in over 1,100 proteins in IFN-β-stimulated cells. In parallel, we compared the substrate selectivity hHERC5 to the major mouse ISG15 ligase, mHERC6, and analysis of sequences surrounding ISGylation sites revealed that hHERC5 and mHERC6 have distinct preferences for amino acid sequence context. Several features of the datasets were consistent with ISGylation of ribosome-tethered nascent chains, and mHERC6, like hHERC5, cotranslationally modified nascent polypeptides. The ISGylome datasets presented here represent the largest numbers of protein targets and modification sites attributable to a single Ub/Ubl ligase and the lysine selectivities of the hHERC5 and mHERC6 enzymes may have implications for the activities of HECT domain ligases, generally.
