Mechanism of phosphoribosyl-ubiquitination mediated by a single Legionella effector.Akturk, A., Wasilko, D.J., Wu, X., Liu, Y., Zhang, Y., Qiu, J., Luo, Z.Q., Reiter, K.H., Brzovic, P.S., Klevit, R.E., Mao, Y.
(2018) Nature 557: 729-733
- PubMed: 29795346
- DOI: 10.1038/s41586-018-0147-6
- Primary Citation of Related Structures:
6B7M, 6B7O, 6B7P, 6B7Q
- PubMed Abstract:
Ubiquitination is a post-translational modification that regulates many cellular processes in eukaryotes 1-4 . The conventional ubiquitination cascade culminates in a covalent linkage between the C terminus of ubiquitin (Ub) and a target protein, usually on a lysine side chain 1,5 ...
Ubiquitination is a post-translational modification that regulates many cellular processes in eukaryotes 1-4 . The conventional ubiquitination cascade culminates in a covalent linkage between the C terminus of ubiquitin (Ub) and a target protein, usually on a lysine side chain 1,5 . Recent studies of the Legionella pneumophila SidE family of effector proteins revealed a ubiquitination method in which a phosphoribosyl ubiquitin (PR-Ub) is conjugated to a serine residue on substrates via a phosphodiester bond 6-8 . Here we present the crystal structure of a fragment of the SidE family member SdeA that retains ubiquitination activity, and determine the mechanism of this unique post-translational modification. The structure reveals that the catalytic module contains two distinct functional units: a phosphodiesterase domain and a mono-ADP-ribosyltransferase domain. Biochemical analysis shows that the mono-ADP-ribosyltransferase domain-mediated conversion of Ub to ADP-ribosylated Ub (ADPR-Ub) and the phosphodiesterase domain-mediated ligation of PR-Ub to substrates are two independent activities of SdeA. Furthermore, we present two crystal structures of a homologous phosphodiesterase domain from the SidE family member SdeD 9 in complexes with Ub and ADPR-Ub. The structures suggest a mechanism for how SdeA processes ADPR-Ub to PR-Ub and AMP, and conjugates PR-Ub to a serine residue in substrates. Our study establishes the molecular mechanism of phosphoribosyl-linked ubiquitination and will enable future studies of this unusual type of ubiquitination in eukaryotes.
Weill Institute for Cell and Molecular Biology and Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA. firstname.lastname@example.org.