Open AccessA structurally conserved site in AUP1 binds the E2 enzyme UBE2G2 and is essential for ER-associated degradation
Author(s) -
Christopher E. Smith,
Ya Chea Tsai,
Yu-He Liang,
Domarin Khago,
Jennifer Mariano,
Jess Li,
Sergey G. Tarasov,
Emma Gergel,
Borong Tsai,
Matthew Villaneuva,
Michelle E. Clapp,
Valentin Magidson,
Raj Chari,
R. Andrew Byrd,
Xinhua Ji,
Allan M. Weissman
Publication year - 2021
Publication title -
plos biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.127
H-Index - 271
eISSN - 1545-7885
pISSN - 1544-9173
DOI - 10.1371/journal.pbio.3001474
Subject(s) - endoplasmic reticulum associated protein degradation , ubiquitin ligase , biology , endoplasmic reticulum , ubiquitin , microbiology and biotechnology , ubiquitin protein ligases , biochemistry , protein degradation , ubiquitin conjugating enzyme , unfolded protein response , gene
Endoplasmic reticulum–associated degradation (ERAD) is a protein quality control pathway of fundamental importance to cellular homeostasis. Although multiple ERAD pathways exist for targeting topologically distinct substrates, all pathways require substrate ubiquitination. Here, we characterize a key role for the UBE2 G2 B inding R egion (G2BR) of the ERAD accessory protein ancient ubiquitous protein 1 (AUP1) in ERAD pathways. This 27-amino acid (aa) region of AUP1 binds with high specificity and low nanomolar affinity to the backside of the ERAD ubiquitin-conjugating enzyme (E2) UBE2G2. The structure of the AUP1 G2BR (G2BR AUP1 ) in complex with UBE2G2 reveals an interface that includes a network of salt bridges, hydrogen bonds, and hydrophobic interactions essential for AUP1 function in cells. The G2BR AUP1 shares significant structural conservation with the G2BR found in the E3 ubiquitin ligase gp78 and in vitro can similarly allosterically activate ubiquitination in conjunction with ERAD E3s. In cells, AUP1 is uniquely required to maintain normal levels of UBE2G2; this is due to G2BR AUP1 binding to the E2 and preventing its rapid degradation. In addition, the G2BR AUP1 is required for both ER membrane recruitment of UBE2G2 and for its activation at the ER membrane. Thus, by binding to the backside of a critical ERAD E2, G2BR AUP1 plays multiple critical roles in ERAD.