N-Terminal Acetylation Acts as an Avidity Enhancer Within an Interconnected Multiprotein Complex

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Science  22 Sep 2011:
DOI: 10.1126/science.1209307


Although most eukaryotic proteins are N-terminally acetylated, structural mechanisms by which N-terminal acetylation mediates protein interactions are largely unknown. Here, we found that N-terminal acetylation of the E2 enzyme, Ubc12, dictates distinctive E3-dependent ligation of the ubiquitin-like protein, Nedd8, to Cul1. Structural, biochemical, biophysical, and genetic analyses revealed how complete burial of Ubc12's N-acetyl-methionine in a hydrophobic pocket in the E3, Dcn1, promotes cullin neddylation. The results suggest that the N-terminal acetyl both directs Ubc12's interactions with Dcn1, and prevents repulsion of a charged N-terminus. Our data provide a link between acetylation and ubiquitin-like protein conjugation, and define a mechanism for N-terminal acetylation-dependent recognition.