Recent Publications (Original)

Yu Pang, Hayashi Yamamoto, Hirokazu Sakamoto, Masahide Oku, Joe Kimanthi Mutungi, Mayurbhai Himatbhai Sahani, Yoshitaka Kurikawa, Kiyoshi Kita, Nobuo N. Noda, Yasuyoshi Sakai, Honglin Jia, and Noboru Mizushima
Evolution from covalent conjugation to non-covalent interaction in the ubiquitin-like ATG12 system
Nat Struct Mol Biol, 2019, March 25 DOI: 10.1038/s41594-019-0204-3

Ubiquitin or ubiquitin-like proteins can be covalently conjugated to multiple proteins that do not necessarily have binding interfaces. Here, we show that an evolutionary transition from covalent conjugation to non-covalent interaction has occurred in the ubiquitin-like autophagy-related 12 (ATG12) conjugation system. ATG12 is covalently conjugated to its sole substrate, ATG5, by a ubiquitylation-like mechanism. However, the apicomplexan parasites Plasmodium and Toxoplasma and some yeast species such as Komagataella phaffii (previously Pichia pastoris) lack the E2-like enzyme ATG10 and the most carboxy (C)-terminal glycine of ATG12, both of which are required for covalent linkage. Instead, ATG12 in these organisms forms a non-covalent complex with ATG5. This non-covalent ATG12–ATG5 complex retains the ability to facilitate ATG8–phosphatidylethanolamine conjugation. These results suggest that ubiquitin-like covalent conjugation can evolve to a simpler non-covalent interaction, most probably when the system has a limited number of targets.

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