Journal article
Distinct Ligand Specificity of the Tiam1 and Tiam2 PDZ Domains
Biochemistry (Easton), Vol.50(8), pp.1296-1308
03/01/2011
DOI: 10.1021/bi1013613
PMCID: PMC3059893
PMID: 21192692
Abstract
Guanine nucleotide exchange factor proteins of the Tiam family are activators of the Rho GTPase Rac1 and critical for cell morphology, adhesion, migration, and polarity. These proteins are modular and contain a variety of interaction domains, including a single
p
ost-synaptic density-95/
d
iscs large/
z
onula occludens-1 (PDZ) domain. Previous studies suggest that the specificities of the Tiam1 and Tiam2 PDZ domains are distinct. Here, we sought to conclusively define these specificities and determine their molecular origin. Using a combinatorial peptide library, we identified a consensus binding sequence for each PDZ domain. Analysis of these consensus sequences and binding assays with peptides derived from native proteins indicated that these two PDZ domains have overlapping, but distinct specificities. We also identified residues in two regions (S
0
and S
-2
pockets) of the Tiam1 PDZ domain that are important determinants of ligand specificity. Site-directed mutagenesis of four non-conserved residues in these two regions along with peptide binding analyses confirmed that these residues are crucial for ligand affinity and specificity. Furthermore, double-mutant cycle analysis of each region revealed energetic couplings that were dependent on the ligand being investigated. Remarkably, a Tiam1 PDZ domain quadruple mutant had the same specificity as the Tiam2 PDZ domain. Finally, analysis of Tiam-family PDZ domain sequences indicated that the PDZ domains segregate into four distinct families based on the residues studied here. Collectively, our data suggest that Tiam-family proteins have highly evolved PDZ-ligand interfaces with distinct specificities, and that they have disparate PDZ-dependent biological functions.
Details
- Title: Subtitle
- Distinct Ligand Specificity of the Tiam1 and Tiam2 PDZ Domains
- Creators
- Tyson R Shepherd - Department of Biochemistry, Roy J. and Lucille A. Carver College of MedicineRyan L Hard - Department of Chemistry and Ohio State Biochemistry Program, The Ohio State University, Columbus, Ohio 43210Ann M Murray - Department of Biochemistry, Roy J. and Lucille A. Carver College of MedicineDehua Pei - Department of Chemistry and Ohio State Biochemistry Program, The Ohio State University, Columbus, Ohio 43210Ernesto J Fuentes - Department of Biochemistry, Roy J. and Lucille A. Carver College of Medicine
- Resource Type
- Journal article
- Publication Details
- Biochemistry (Easton), Vol.50(8), pp.1296-1308
- DOI
- 10.1021/bi1013613
- PMID
- 21192692
- PMCID
- PMC3059893
- NLM abbreviation
- Biochemistry
- ISSN
- 0006-2960
- eISSN
- 1520-4995
- Language
- English
- Date published
- 03/01/2011
- Academic Unit
- Biochemistry and Molecular Biology
- Record Identifier
- 9984024526702771
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