Regulation of Smurf2 ubiquitin ligase activity by anchoring the E2 to the HECT domain

Abiodun A Ogunjimi; Douglas J Briant; Nadia Pece-Barbara; Christine Le Roy; Gianni M Di Guglielmo; Peter Kavsak; Richele K Rasmussen; Bruce T Seet; Frank Sicheri; Jeffrey L Wrana

doi:10.1016/j.molcel.2005.06.028

Regulation of Smurf2 ubiquitin ligase activity by anchoring the E2 to the HECT domain

Mol Cell. 2005 Aug 5;19(3):297-308. doi: 10.1016/j.molcel.2005.06.028.

Authors

Abiodun A Ogunjimi¹, Douglas J Briant, Nadia Pece-Barbara, Christine Le Roy, Gianni M Di Guglielmo, Peter Kavsak, Richele K Rasmussen, Bruce T Seet, Frank Sicheri, Jeffrey L Wrana

Affiliation

¹ Programme in Molecular Biology and Cancer, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario M5G 1X5, Canada.

PMID: 16061177
DOI: 10.1016/j.molcel.2005.06.028

Abstract

The conjugation of ubiquitin to proteins involves a cascade of activating (E1), conjugating (E2), and ubiquitin-ligating (E3) type enzymes that commonly signal protein destruction. In TGFbeta signaling the inhibitory protein Smad7 recruits Smurf2, an E3 of the C2-WW-HECT domain class, to the TGFbeta receptor complex to facilitate receptor degradation. Here, we demonstrate that the amino-terminal domain (NTD) of Smad7 stimulates Smurf activity by recruiting the E2, UbcH7, to the HECT domain. A 2.1 A resolution X-ray crystal structure of the Smurf2 HECT domain reveals that it has a suboptimal E2 binding pocket that could be optimized by mutagenesis to generate a HECT domain that functions independently of Smad7 and potently inhibits TGFbeta signaling. Thus, E2 enzyme recognition by an E3 HECT enzyme is not constitutively competent and provides a point of control for regulating the ubiquitin ligase activity through the action of auxiliary proteins.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Amino Acid Motifs / genetics
Amino Acid Sequence
Binding Sites / genetics
Catalysis
Cell Line
Crystallography, X-Ray
DNA-Binding Proteins / genetics
DNA-Binding Proteins / metabolism*
DNA-Binding Proteins / physiology
Enzyme Activation
Humans
Models, Molecular
Molecular Sequence Data
Mutagenesis, Site-Directed
Mutation
Peptide Fragments / genetics
Protein Binding
Protein Structure, Tertiary
Receptors, Transforming Growth Factor beta / genetics
Receptors, Transforming Growth Factor beta / metabolism
Recombinant Proteins / metabolism
Sequence Homology, Amino Acid
Signal Transduction / physiology
Smad7 Protein
Trans-Activators / genetics
Trans-Activators / metabolism*
Trans-Activators / physiology
Transfection
Ubiquitin / metabolism
Ubiquitin-Activating Enzymes / metabolism
Ubiquitin-Conjugating Enzymes / chemistry
Ubiquitin-Conjugating Enzymes / genetics
Ubiquitin-Conjugating Enzymes / metabolism*
Ubiquitin-Protein Ligases / chemistry
Ubiquitin-Protein Ligases / genetics
Ubiquitin-Protein Ligases / metabolism*
Ubiquitin-Protein Ligases / physiology

Substances

DNA-Binding Proteins
Peptide Fragments
Receptors, Transforming Growth Factor beta
Recombinant Proteins
SMAD7 protein, human
Smad7 Protein
Trans-Activators
Ubiquitin
UBE2L3 protein, human
Ubiquitin-Conjugating Enzymes
SMURF2 protein, human
Ubiquitin-Protein Ligases
Ubiquitin-Activating Enzymes