Analysis of ubiquitin recognition by the HECT ligase E6AP provides insight into its linkage specificity
| Autor: | Eric R. Strieter, Kirandeep K. Deol, Sonja Lorenz, Bodo Sander, Marie-Annick Letzelter, Lena K. Ries |
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| Rok vydání: | 2019 |
| Předmět: |
0301 basic medicine
Ubiquitin-Protein Ligases Mutation Missense medicine.disease_cause ubiquitin ligase Biochemistry Catalysis Substrate Specificity 03 medical and health sciences Ubiquitin Catalytic Domain ddc:570 medicine UBE3A Humans enzyme mechanism ubiquitylation (ubiquitination) Molecular Biology chemistry.chemical_classification Mutation Isopeptide bond DNA ligase 030102 biochemistry & molecular biology biology C-terminus Cell Biology Cell biology Ubiquitin ligase 030104 developmental biology post-translational modification Amino Acid Substitution chemistry Catalytic cycle Enzymology biology.protein |
| Zdroj: | The Journal of Biological Chemistry Journal of Biological Chemistry |
| ISSN: | 0021-9258 |
| Popis: | Deregulation of the HECT-type ubiquitin ligase E6AP (UBE3A) is implicated in human papilloma virus-induced cervical tumorigenesis and several neurodevelopmental disorders. Yet the structural underpinnings of activity and specificity in this crucial ligase are incompletely understood. Here, we unravel the determinants of ubiquitin recognition by the catalytic domain of E6AP and assign them to particular steps in the catalytic cycle. We identify a functionally critical interface that is specifically required during the initial formation of a thioester-linked intermediate between the C terminus of ubiquitin and the ligase-active site. This interface resembles the one utilized by NEDD4-type enzymes, indicating that it is widely conserved across HECT ligases, independent of their linkage specificities. Moreover, we uncover surface regions in ubiquitin and E6AP, both in the N- and C-terminal portions of the catalytic domain, that are important for the subsequent reaction step of isopeptide bond formation between two ubiquitin molecules. We decipher key elements of linkage specificity, including the C-terminal tail of E6AP and a hydrophilic surface region of ubiquitin in proximity to the acceptor site Lys-48. Intriguingly, mutation of Glu-51, a single residue within this region, permits formation of alternative chain types, thus pointing to a key role of ubiquitin in conferring linkage specificity to E6AP. We speculate that substrate-assisted catalysis, as described previously for certain RING-associated ubiquitin–conjugating enzymes, constitutes a common principle during linkage-specific ubiquitin chain assembly by diverse classes of ubiquitination enzymes, including HECT ligases. |
| Databáze: | OpenAIRE |
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