Structure of a compact conformation of linear diubiquitin
Abstract:Post‐translational modifications involving ubiquitin regulate a wide range of biological processes including protein degradation, responses to DNA damage and immune signalling. Ubiquitin polymerizes into chains which may contain eight different linkage types; the ubiquitin C‐terminal glycine can link to one of the seven lysine residues or the N‐terminal amino group of methionine in the distal ubiquitin molecule. The latter head‐to‐tail linkage type, referred to as a linear ubiquitin chain, is involved in NF‐κB activation through specific interactions with NF‐κB essential modulator (NEMO). Here, a crystal structure of linear diubiquitin at a resolution of 2.2 Å is reported. Although the two ubiquitin moieties do not interact with each other directly, the overall structure adopts a compact but not completely closed conformation with a few intermoiety contacts. This structure differs from the previously reported extended conformation, which resembles Lys63‐linked diubiquitin, suggesting that the linear polyubiquitin chain is intrinsically flexible and can adopt multiple conformations.
Document Type: Research Article
Publication date: 2012-02-01