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A dual E3 mechanism for Rub1 ligation to Cdc53.

ABSTRACT: In ubiquitin-like protein (UBL) cascades, a thioester-linked E2?UBL complex typically interacts with an E3 enzyme for UBL transfer to the target. Here we demonstrate a variant mechanism, whereby the E2 Ubc12 functions with two E3s, Hrt1 and Dcn1, for ligation of the UBL Rub1 to Cdc53's WHB subdomain. Hrt1 functions like a conventional RING E3, with its N terminus recruiting Cdc53 and C-terminal RING activating Ubc12?Rub1. Dcn1's "potentiating neddylation" domain (Dcn1(P)) acts as an additional E3, reducing nonspecific Hrt1-mediated Ubc12?Rub1 discharge and directing Ubc12's active site to Cdc53. Crystal structures of Dcn1(P)-Cdc53(WHB) and Ubc12 allow modeling of a catalytic complex, supported by mutational data. We propose that Dcn1's interactions with both Cdc53 and Ubc12 would restrict the otherwise flexible Hrt1 RING-bound Ubc12?Rub1 to a catalytically competent orientation. Our data reveal mechanisms by which two E3s function synergistically to promote UBL transfer from one E2 to a target.

SUBMITTER: Scott DC

PROVIDER: S-EPMC3001161 | biostudies-literature | 2010 Sep

REPOSITORIES: biostudies-literature

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A dual E3 mechanism for Rub1 ligation to Cdc53.

Scott Daniel C DC Monda Julie K JK Grace Christy R R CR Duda David M DM Kriwacki Richard W RW Kurz Thimo T Schulman Brenda A BA

Molecular cell 20100901 5

In ubiquitin-like protein (UBL) cascades, a thioester-linked E2∼UBL complex typically interacts with an E3 enzyme for UBL transfer to the target. Here we demonstrate a variant mechanism, whereby the E2 Ubc12 functions with two E3s, Hrt1 and Dcn1, for ligation of the UBL Rub1 to Cdc53's WHB subdomain. Hrt1 functions like a conventional RING E3, with its N terminus recruiting Cdc53 and C-terminal RING activating Ubc12∼Rub1. Dcn1's "potentiating neddylation" domain (Dcn1(P)) acts as an additional E ...[more]

PMID: 20832729

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