PDBsum entry 6ulh

Transferase

PDB id: 6ulh

Contents

Protein chains

376 a.a.

145 a.a.

76 a.a.

Waters ×272

References listed in PDB file

Key reference

• Title: Legionella effector mavc targets the ube2n~ub conjugate for noncanonical ubiquitination.
• Authors: K.Puvar, S.Iyer, J.Fu, S.Kenny, K.I.Negrón terón, Z.Q.Luo, P.S.Brzovic, R.E.Klevit, C.Das.
• Ref.: Nat Commun, 2020, 11, 2365. [DOI no: 10.1038/s41467-020-16211-x]
• PubMed id: 32398758

Abstract

The bacterial effector MavC modulates the host immune response by blocking Ube2N activity employing an E1-independent ubiquitin ligation, catalyzing formation of a γ-glutamyl-ε-Lys (Gln40^Ub-Lys92^Ube2N) isopeptide crosslink using a transglutaminase mechanism. Here we provide biochemical evidence in support of MavC targeting the activated, thioester-linked Ube2N~ubiquitin conjugate, catalyzing an intramolecular transglutamination reaction, covalently crosslinking the Ube2N and Ub subunits effectively inactivating the E2~Ub conjugate. Ubiquitin exhibits weak binding to MavC alone, but shows an increase in affinity when tethered to Ube2N in a disulfide-linked substrate that mimics the charged E2~Ub conjugate. Crystal structures of MavC in complex with the substrate mimic and crosslinked product provide insights into the reaction mechanism and underlying protein dynamics that favor transamidation over deamidation, while revealing a crucial role for the structurally unique insertion domain in substrate recognition. This work provides a structural basis of ubiquitination by transglutamination and identifies this enzyme's true physiological substrate.