Allosteric activation of E2-RING finger-mediated ubiquitylation by a structurally defined specific E2-binding region of gp78.
The activity of RING finger ubiquitin ligases (E3) is dependent on their ability to facilitate transfer of ubiquitin from ubiquitin-conjugating enzymes (E2) to substrates. The G2BR domain within the E3 gp78 binds selectively and with high affinity to the E2 Ube2g2. Through structural and functional analyses, we determine that this occurs on a region of Ube2g2 distinct from binding sites for ubiquitin-activating enzyme (E1) and RING fingers. Binding to the G2BR results in conformational changes in Ube2g2 that affect ubiquitin loading. The Ube2g2:G2BR interaction also causes an approximately 50-fold increase in affinity between the E2 and RING finger. This results in markedly increased ubiquitylation by Ube2g2 and the gp78 RING finger. The significance of this G2BR effect is underscored by enhanced ubiquitylation observed when Ube2g2 is paired with other RING finger E3s. These findings uncover a mechanism whereby allosteric effects on an E2 enhance E2-RING finger interactions and, consequently, ubiquitylation.
Das
Ranabir
R
Structural Biophysics Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702-1201, USA.
Mariano
Jennifer
J
Tsai
Yien Che
YC
Kalathur
Ravi C
RC
Kostova
Zlatka
Z
Li
Jess
J
Tarasov
Sergey G
SG
McFeeters
Robert L
RL
Altieri
Amanda S
AS
Ji
Xinhua
X
Byrd
R Andrew
RA
Weissman
Allan M
AM
D000595:Amino Acid Sequence; D001665:Binding Sites; D018360:Crystallography, X-Ray; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D017434:Protein Structure, Tertiary; D054829:RING Finger Domains; D060285:Receptors, Autocrine Motility Factor; D018121:Receptors, Cytokine / Q000737:chemistry* / Q000378:metabolism / Q000502:physiology; D025801:Ubiquitin / Q000378:metabolism; D044763:Ubiquitin-Conjugating Enzymes / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000737:chemistry* / Q000378:metabolism / Q000502:physiology; D054875:Ubiquitination
D018121:Receptors, Cytokine; D025801:Ubiquitin; C471617:UBE2G2 protein, human; D044763:Ubiquitin-Conjugating Enzymes; C555000:AMFR protein, human; D060285:Receptors, Autocrine Motility Factor; D044767:Ubiquitin-Protein Ligases