Solution structure of the flexible class II ubiquitin-conjugating enzyme Ubc1 provides insights for polyubiquitin chain assembly.

摘要: E2 conjugating enzymes form a thiol ester intermediate with ubiquitin, which is subsequently transferred to substrate protein targeted for degradation. While all proteins comprise catalytic domain where the formed, several E2s (class II) have C-terminal extensions proposed control recognition, dimerization, or polyubiquitin chain formation. Here we present novel solution structure of class II enzyme Ubc1 from Saccharomyces cerevisiae. The shows N-terminal adopts an α/β fold typical other proteins. This physically separated its by 22-residue flexible tether. three-helix bundle that identified as ubiquitin-associated (UBA). NMR chemical shift perturbation experiments show this UBA interacts in regioselective manner ubiquitin. two-domain was used identify UBA-containing proteins, including human E2-25K, likely similar architecture and determine role facilitating