The Tiam1 guanine nucleotide exchange factor is auto-inhibited by its pleckstrin homology coiled-coil extension domain

Zhen Xu; Lokesh Gakhar; Fletcher E Bain; Maria Spies; Ernesto J Fuentes

doi:10.1074/jbc.M117.799114

Back

The Tiam1 guanine nucleotide exchange factor is auto-inhibited by its pleckstrin homology coiled-coil extension domain

Journal article

Open access

Peer reviewed

The Tiam1 guanine nucleotide exchange factor is auto-inhibited by its pleckstrin homology coiled-coil extension domain

Zhen Xu, Lokesh Gakhar, Fletcher E Bain, Maria Spies and Ernesto J Fuentes

The Journal of biological chemistry, Vol.292(43), pp.17777-17793

10/27/2017

DOI: 10.1074/jbc.M117.799114

PMCID: PMC5663878

PMID: 28882897

Files and links (1)

url

https://doi.org/10.1074/jbc.M117.799114View

Published (Version of record) Open Access

Abstract

T-cell lymphoma invasion and metastasis 1 (Tiam1) is a Dbl-family guanine nucleotide exchange factor (GEF) that specifically activates the Rho-family GTPase Rac1 in response to upstream signals, thereby regulating cellular processes including cell adhesion and migration. Tiam1 contains multiple domains, including an N-terminal pleckstrin homology coiled-coiled extension (PH -CC-Ex) and catalytic Dbl homology and C-terminal pleckstrin homology (DH-PH ) domain. Previous studies indicate that larger fragments of Tiam1, such as the region encompassing the N-terminal to C-terminal pleckstrin homology domains (PH -PH ), are auto-inhibited. However, the domains in this region responsible for inhibition remain unknown. Here, we show that the PH -CC-Ex domain inhibits Tiam1 GEF activity by directly interacting with the catalytic DH-PH domain, preventing Rac1 binding and activation. Enzyme kinetics experiments suggested that Tiam1 is auto-inhibited through occlusion of the catalytic site rather than by allostery. Small angle X-ray scattering and ensemble modeling yielded models of the PH -PH fragment that indicate it is in equilibrium between "open" and "closed" conformational states. Finally, single-molecule experiments support a model in which conformational sampling between the open and closed states of Tiam1 contributes to Rac1 dissociation. Our results highlight the role of the PH -CC-Ex domain in Tiam1 GEF regulation and suggest a combinatorial model for GEF inhibition and activation of the Rac1 signaling pathway.

Guanine Nucleotide Exchange Factors - genetics

Humans

Guanine Nucleotide Exchange Factors - metabolism

X-Ray Diffraction

Protein Binding

Signal Transduction - physiology

Kinetics

rac1 GTP-Binding Protein - chemistry

Pleckstrin Homology Domains

T-Lymphoma Invasion and Metastasis-inducing Protein 1

rac1 GTP-Binding Protein - metabolism

Guanine Nucleotide Exchange Factors - chemistry

rac1 GTP-Binding Protein - genetics

Details

Title: Subtitle: The Tiam1 guanine nucleotide exchange factor is auto-inhibited by its pleckstrin homology coiled-coil extension domain
Creators: Zhen Xu - From the Department of Biochemistry
Lokesh Gakhar - Protein Crystallography Facility, and
Fletcher E Bain - From the Department of Biochemistry
Maria Spies - Holden Comprehensive Cancer Center, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242
Ernesto J Fuentes - Holden Comprehensive Cancer Center, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242
Resource Type: Journal article
Publication Details: The Journal of biological chemistry, Vol.292(43), pp.17777-17793
DOI: 10.1074/jbc.M117.799114
PMID: 28882897
PMCID: PMC5663878
NLM abbreviation: J Biol Chem
ISSN: 0021-9258
eISSN: 1083-351X
Publisher: United States
Grant note: R01 GM108617 / NIGMS NIH HHS P30 CA086862 / NCI NIH HHS
Language: English
Date published: 10/27/2017
Academic Unit: Radiation Oncology; Biochemistry and Molecular Biology; Medicine Administration
Record Identifier: 9984024407402771

Metrics

26 Record Views

15 Times Cited - Web of Science