Solution Structure of the Phosphotyrosine Binding (PTB) Domain of Human Tensin2 Protein in Complex with Deleted in Liver Cancer 1 (DLC1) Peptide Reveals a Novel Peptide Binding Mode

Lihong Chen,Changdong Liu,Frankie Chi Fat Ko,Naining Xu,Irene Oi-Lin Ng,Judy Wai Ping Yam,Guang Zhu

doi:10.1074/jbc.m112.360206

Abstract

The protein deleted in liver cancer 1 (DLC1) interacts with the tensin family of focal adhesion proteins to play a role as a tumor suppressor in a wide spectrum of human cancers. This interaction has been proven to be crucial to the oncogenic inhibitory capacity and focal adhesion localization of DLC1. The phosphotyrosine binding (PTB) domain of tensin2 predominantly interacts with a novel site on DLC1, not the canonical NPXY motif. In this study, we characterized this interaction biochemically and determined the complex structure of tensin2 PTB domain with DLC1 peptide by NMR spectroscopy. Our HADDOCK-derived complex structure model elucidates the molecular mechanism by which tensin2 PTB domain recognizes DLC1 peptide and reveals a PTB-peptide binding mode that is unique in that peptide occupies the binding site opposite to the canonical NPXY motif interaction site with the peptide utilizing a non-canonical binding motif to bind in an extended conformation and that the N-terminal helix, which is unique to some Shc- and Dab-like PTB domains, is required for binding. Mutations of crucial residues defined for the PTB-DLC1 interaction affected the co-localization of DLC1 and tensin2 in cells and abolished DLC1-mediated growth suppression of hepatocellular carcinoma cells. This tensin2 PTB-DLC1 peptide complex with a novel binding mode extends the versatile binding repertoire of the PTB domains in mediating diverse cellular signaling pathways as well as provides a molecular and structural basis for better understanding the tumor-suppressive activity of DLC1 and tensin2.

Highlights

deleted in liver cancer 1 (DLC1) interacts with tensin2 phosphotyrosine binding (PTB), playing a role as a tumor suppressor in many human cancers
Our HADDOCK-derived complex structure model elucidates the molecular mechanism by which tensin2 PTB domain recognizes DLC1 peptide and reveals a PTB-peptide binding mode that is unique in that peptide occupies the binding site opposite to the canonical NPXY motif interaction site with the peptide utilizing a non-canonical binding motif to bind in an extended conformation and that the N-terminal helix, which is unique to some Shc- and Dab-like PTB domains, is required for binding
Binding Studies of Tensin2 PTB Domain and the DLC1 Peptide—In a previous study, we identified that amino acids 375–385 of DLC1 were responsible for binding the PTB domain of tensin2 [26] (Fig. 1A)

Summary

Background

DLC1 interacts with tensin PTB, playing a role as a tumor suppressor in many human cancers. Conclusion: The novel PTB-peptide binding mode provides a molecular basis for understanding the tumor suppression of DLC1 and tensin. Plex with a novel binding mode extends the versatile binding repertoire of the PTB domains in mediating diverse cellular signaling pathways as well as provides a molecular and structural basis for better understanding the tumor-suppressive activity of DLC1 and tensin. Tensin PTB-DLC1 Complex Reveals Novel Peptide Binding Mode a family of proteins localized at integrin-mediated focal adhesions bridging the actin cytoskeleton and integrins [14]. The HADDOCKderived complex structural model reported here reveals a novel peptide binding mode and expands the recognition modes of PTB domains beyond the canonical NPX(p)Y-like motif (where pY is phosphotyrosine) in mediating diverse cellular signaling pathways

EXPERIMENTAL PROCEDURES

RESULTS

DISCUSSION