Abstract
Grb2-Sos1 interaction, mediated by the canonical binding of N-terminal SH3 (nSH3) and C-terminal SH3 (cSH3) domains of Grb2 to a proline-rich sequence in Sos1, provides a key regulatory switch that relays signaling from activated receptor tyrosine kinases to downstream effector molecules such as Ras. Here, using isothermal titration calorimetry in combination with site-directed mutagenesis, we show that the nSH3 domain binds to a Sos1-derived peptide containing the proline-rich consensus motif PPVPPR with an affinity that is nearly threefold greater than that observed for the binding of cSH3 domain. We further demonstrate that such differential binding of nSH3 domain relative to the cSH3 domain is largely due to the requirement of a specific acidic residue in the RT loop of the β-barrel fold to engage in the formation of a salt bridge with the arginine residue in the consensus motif PPVPPR. While this role is fulfilled by an optimally positioned D15 in the nSH3 domain, the chemically distinct and structurally non-equivalent E171 substitutes in the case of the cSH3 domain. Additionally, our data suggest that salt tightly modulates the binding of both SH3 domains to Sos1 in a thermodynamically distinct manner. Our data further reveal that, while binding of both SH3 domains to Sos1 is under enthalpic control, the nSH3 binding suffers from entropic penalty in contrast to entropic gain accompanying the binding of cSH3, implying that the two domains employ differential thermodynamic mechanisms for Sos1 recognition. Our new findings are rationalized in the context of 3D structural models of SH3 domains in complex with the Sos1 peptide. Taken together, our study provides structural basis of the differential binding of SH3 domains of Grb2 to Sos1 and a detailed thermodynamic profile of this key protein-protein interaction pertinent to cellular signaling and cancer.
| Original language | English |
|---|---|
| Pages (from-to) | 52-62 |
| Number of pages | 11 |
| Journal | Archives of Biochemistry and Biophysics |
| Volume | 479 |
| Issue number | 1 |
| DOIs | |
| State | Published - Nov 1 2008 |
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Keywords
- Grb2 adaptor
- Guanine nucleotide exchange factor Sos1
- Isothermal titration calorimetry
- Protein-ligand thermodynamics
- SH3 domain
ASJC Scopus subject areas
- Biochemistry
- Biophysics
- Molecular Biology
Cite this
Structural basis of the differential binding of the SH3 domains of Grb2 adaptor to the guanine nucleotide exchange factor Sos1. / McDonald, Caleb B.; Seldeen, Kenneth L.; Deegan, Brian J.; Farooq, Amjad.
In: Archives of Biochemistry and Biophysics, Vol. 479, No. 1, 01.11.2008, p. 52-62.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Structural basis of the differential binding of the SH3 domains of Grb2 adaptor to the guanine nucleotide exchange factor Sos1
AU - McDonald, Caleb B.
AU - Seldeen, Kenneth L.
AU - Deegan, Brian J.
AU - Farooq, Amjad
PY - 2008/11/1
Y1 - 2008/11/1
N2 - Grb2-Sos1 interaction, mediated by the canonical binding of N-terminal SH3 (nSH3) and C-terminal SH3 (cSH3) domains of Grb2 to a proline-rich sequence in Sos1, provides a key regulatory switch that relays signaling from activated receptor tyrosine kinases to downstream effector molecules such as Ras. Here, using isothermal titration calorimetry in combination with site-directed mutagenesis, we show that the nSH3 domain binds to a Sos1-derived peptide containing the proline-rich consensus motif PPVPPR with an affinity that is nearly threefold greater than that observed for the binding of cSH3 domain. We further demonstrate that such differential binding of nSH3 domain relative to the cSH3 domain is largely due to the requirement of a specific acidic residue in the RT loop of the β-barrel fold to engage in the formation of a salt bridge with the arginine residue in the consensus motif PPVPPR. While this role is fulfilled by an optimally positioned D15 in the nSH3 domain, the chemically distinct and structurally non-equivalent E171 substitutes in the case of the cSH3 domain. Additionally, our data suggest that salt tightly modulates the binding of both SH3 domains to Sos1 in a thermodynamically distinct manner. Our data further reveal that, while binding of both SH3 domains to Sos1 is under enthalpic control, the nSH3 binding suffers from entropic penalty in contrast to entropic gain accompanying the binding of cSH3, implying that the two domains employ differential thermodynamic mechanisms for Sos1 recognition. Our new findings are rationalized in the context of 3D structural models of SH3 domains in complex with the Sos1 peptide. Taken together, our study provides structural basis of the differential binding of SH3 domains of Grb2 to Sos1 and a detailed thermodynamic profile of this key protein-protein interaction pertinent to cellular signaling and cancer.
AB - Grb2-Sos1 interaction, mediated by the canonical binding of N-terminal SH3 (nSH3) and C-terminal SH3 (cSH3) domains of Grb2 to a proline-rich sequence in Sos1, provides a key regulatory switch that relays signaling from activated receptor tyrosine kinases to downstream effector molecules such as Ras. Here, using isothermal titration calorimetry in combination with site-directed mutagenesis, we show that the nSH3 domain binds to a Sos1-derived peptide containing the proline-rich consensus motif PPVPPR with an affinity that is nearly threefold greater than that observed for the binding of cSH3 domain. We further demonstrate that such differential binding of nSH3 domain relative to the cSH3 domain is largely due to the requirement of a specific acidic residue in the RT loop of the β-barrel fold to engage in the formation of a salt bridge with the arginine residue in the consensus motif PPVPPR. While this role is fulfilled by an optimally positioned D15 in the nSH3 domain, the chemically distinct and structurally non-equivalent E171 substitutes in the case of the cSH3 domain. Additionally, our data suggest that salt tightly modulates the binding of both SH3 domains to Sos1 in a thermodynamically distinct manner. Our data further reveal that, while binding of both SH3 domains to Sos1 is under enthalpic control, the nSH3 binding suffers from entropic penalty in contrast to entropic gain accompanying the binding of cSH3, implying that the two domains employ differential thermodynamic mechanisms for Sos1 recognition. Our new findings are rationalized in the context of 3D structural models of SH3 domains in complex with the Sos1 peptide. Taken together, our study provides structural basis of the differential binding of SH3 domains of Grb2 to Sos1 and a detailed thermodynamic profile of this key protein-protein interaction pertinent to cellular signaling and cancer.
KW - Grb2 adaptor
KW - Guanine nucleotide exchange factor Sos1
KW - Isothermal titration calorimetry
KW - Protein-ligand thermodynamics
KW - SH3 domain
UR - http://www.scopus.com/inward/record.url?scp=53649101157&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=53649101157&partnerID=8YFLogxK
U2 - 10.1016/j.abb.2008.08.012
DO - 10.1016/j.abb.2008.08.012
M3 - Article
C2 - 18778683
AN - SCOPUS:53649101157
VL - 479
SP - 52
EP - 62
JO - Archives of Biochemistry and Biophysics
JF - Archives of Biochemistry and Biophysics
SN - 0003-9861
IS - 1
ER -