CUL3-KBTBD6/KBTBD7 ubiquitin ligase cooperates with GABARAP proteins to spatially restrict TIAM1-RAC1 signaling

Heide Marika Genau; Jessica Huber; Francesco Baschieri; Masato Akutsu; Volker Dötsch; Hesso Farhan; Vladimir Rogov; Christian Behrends

doi:10.1016/j.molcel.2014.12.040

CUL3-KBTBD6/KBTBD7 ubiquitin ligase cooperates with GABARAP proteins to spatially restrict TIAM1-RAC1 signaling

Mol Cell. 2015 Mar 19;57(6):995-1010. doi: 10.1016/j.molcel.2014.12.040. Epub 2015 Feb 12.

Authors

Heide Marika Genau¹, Jessica Huber², Francesco Baschieri³, Masato Akutsu⁴, Volker Dötsch², Hesso Farhan³, Vladimir Rogov², Christian Behrends⁵

Affiliations

¹ Institute of Biochemistry II, Goethe University School of Medicine, 60590 Frankfurt am Main, Germany.
² Institute of Biophysical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe University, 60438 Frankfurt am Main, Germany.
³ Department of Biology, University of Konstanz, 78464 Konstanz, Germany; Biotechnology Institute Thurgau, 8280 Kreuzlingen, Switzerland.
⁴ Buchmann Institute for Molecular Life Sciences, Goethe University, 60438 Frankfurt am Main, Germany.
⁵ Institute of Biochemistry II, Goethe University School of Medicine, 60590 Frankfurt am Main, Germany. Electronic address: behrends@em.uni-frankfurt.de.

PMID: 25684205
DOI: 10.1016/j.molcel.2014.12.040

Abstract

The small Rho GTPase RAC1 is an essential regulator of cellular signaling that controls actin rearrangements and cell motility. Here, we identify a novel CUL3 RING ubiquitin ligase complex, containing the substrate adaptors KBTBD6 and KBTBD7, that mediates ubiquitylation and proteasomal degradation of TIAM1, a RAC1-specific GEF. Increasing the abundance of TIAM1 by depletion of KBTBD6 and/or KBTBD7 leads to elevated RAC1 activity, changes in actin morphology, loss of focal adhesions, reduced proliferation, and enhanced invasion. KBTBD6 and KBTBD7 employ ATG8 family-interacting motifs to bind preferentially to GABARAP proteins. Surprisingly, ubiquitylation and degradation of TIAM1 by CUL3(KBTBD6/KBTBD7) depends on its binding to GABARAP proteins. Our study reveals that recruitment of CUL3(KBTBD6/KBTBD7) to GABARAP-containing vesicles regulates the abundance of membrane-associated TIAM1 and subsequently spatially restricted RAC1 signaling. Besides their role in autophagy and trafficking, we uncovered a previously unknown function of GABARAP proteins as membrane-localized signaling scaffolds.

Publication types

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

MeSH terms

Adaptor Proteins, Signal Transducing / chemistry
Adaptor Proteins, Signal Transducing / genetics
Adaptor Proteins, Signal Transducing / metabolism*
Amino Acid Sequence
Apoptosis Regulatory Proteins
Autophagy-Related Protein 8 Family
Cullin Proteins / genetics
Cullin Proteins / metabolism*
Guanine Nucleotide Exchange Factors / genetics
Guanine Nucleotide Exchange Factors / metabolism*
Humans
Intracellular Signaling Peptides and Proteins
Microfilament Proteins / metabolism
Microtubule-Associated Proteins / chemistry
Microtubule-Associated Proteins / genetics
Microtubule-Associated Proteins / metabolism*
Models, Molecular
Molecular Sequence Data
Multiprotein Complexes / genetics
Multiprotein Complexes / metabolism
Nuclear Magnetic Resonance, Biomolecular
Protein Conformation
Protein Multimerization
Signal Transduction
T-Lymphoma Invasion and Metastasis-inducing Protein 1
Trans-Activators / genetics
Trans-Activators / metabolism*
Ubiquitination
rac1 GTP-Binding Protein / genetics
rac1 GTP-Binding Protein / metabolism*

Substances

Adaptor Proteins, Signal Transducing
Apoptosis Regulatory Proteins
Autophagy-Related Protein 8 Family
CUL3 protein, human
Cullin Proteins
GABARAP protein, human
GABARAPL2 protein, human
Guanine Nucleotide Exchange Factors
Intracellular Signaling Peptides and Proteins
KBTBD6 protein, human
KBTBD7 protein, human
Microfilament Proteins
Microtubule-Associated Proteins
Multiprotein Complexes
RAC1 protein, human
T-Lymphoma Invasion and Metastasis-inducing Protein 1
TIAM1 protein, human
Trans-Activators
rac1 GTP-Binding Protein

Associated data

PDB/4XC2