Ubiquitin acetylation inhibits polyubiquitin chain elongation

• Published in: EMBO reports Vol. 16; no. 2; pp. 192 - 201
• Main Authors: Ohtake, Fumiaki, Saeki, Yasushi, Sakamoto, Kensaku, Ohtake, Kazumasa, Nishikawa, Hiroyuki, Tsuchiya, Hikaru, Ohta, Tomohiko, Tanaka, Keiji, Kanno, Jun
• Format: Journal Article
• Language: English
• Published: London Blackwell Publishing Ltd 01.02.2015; Nature Publishing Group UK; BlackWell Publishing Ltd
• Subjects: Acetylation; EMBO31; Enzymes; Humans; mechanism; Molecular biology; Polyubiquitin - metabolism; post-translational modification; Protein Processing, Post-Translational; Proteins; Scientific Report; Scientific Reports; Substrates; ubiquitin; Ubiquitin - metabolism; Ubiquitination; acetylation; mechanism; ubiquitin; post‐translational modification
• ISSN: 1469-221X; 1469-3178
• DOI: 10.15252/embr.201439152

Ubiquitylation is a versatile post‐translational modification (PTM). The diversity of ubiquitylation topologies, which encompasses different chain lengths and linkages, underlies its widespread cellular roles. Here, we show that endogenous ubiquitin is acetylated at lysine (K)‐6 (AcK6) or K48. Acetylated ubiquitin does not affect substrate monoubiquitylation, but inhibits K11‐, K48‐, and K63‐linked polyubiquitin chain elongation by several E2 enzymes in vitro . In cells, AcK6‐mimetic ubiquitin stabilizes the monoubiquitylation of histone H2B—which we identify as an endogenous substrate of acetylated ubiquitin—and of artificial ubiquitin fusion degradation substrates. These results characterize a mechanism whereby ubiquitin, itself a PTM, is subject to another PTM to modulate mono‐ and polyubiquitylation, thus adding a new regulatory layer to ubiquitin biology. Synopsis This study shows that endogenous ubiquitin can be acetylated at K6 or K48. This modification inhibits K11‐, K48‐, and K63‐linked chain elongation, leading to the accumulation of monoubiquitylated substrates, and adding a new layer of regulation in the ubiquitin system. Acetylation and phosphorylation were identified in substrate‐conjugated ubiquitin in mammalian cells. Ubiquitin acetylation affects the noncovalent interaction of ubiquitin with E2 enzymes. Acetylation at K6/K48 represses polyubiquitylation with K11/K48/K63 linkages. Graphical Abstract This study shows that endogenous ubiquitin is acetylated at K6 and K48. This inhibits K11‐, K48‐ and K63‐linked chain elongation, leading to the accumulation of monoubiquitylated substrates, and adding a new layer of regulation in the ubiquitin system.