Structural model of the TRPP2/PKD1 C-terminal coiled-coil complex produced by a combined computational and
Jiang Zhu1, Yong Yu, Maximilian H Ulbrich
1Department of Biochemistry and Molecular Biophysics, Howard Hughes Medical Institute and Center for Computational Biology and Bioinformatics, Columbia University, New York, NY 10032, USA.
Abstract:
Autosomal dominant polycystic kidney disease (ADPKD) is caused by mutations in TRPP2 and PKD1, which form an ion channel/receptor complex containing three TRPP2 and one PKD1. A TRPP2 C-terminal coiled-coil trimer, critical for the assembly of this complex, associates with a single PKD1 C-terminal coiled-coil. Many ADPKD pathogenic mutations result in the abolishment of the TRPP2/PKD1 coiled-coil complex. To gain molecular and functional insights into this heterotetrameric complex, we computationally constructed a structural model by using a two-step docking strategy, based on a known crystal structure of the TRPP2 coiled-coil trimer. The model shows that this tetrameric complex has a novel di-trimer configuration: An upstream trimer made of three TRPP2 helices and a downstream trimer made of two TRPP2 helices and one PKD1 helix. Mutagenesis and biochemical analysis identified critical TRPP2/PKD1 interface contacts essential for the heteromeric coiled-coil complex. Mutation of these interface positions in the full-length proteins showed that these interactions were critical for the assembly of the full-length complex in cells. Our results provide a means to specifically weaken the TRPP2 and PKD1 association, thus facilitating future in vitro and in vivo studies on the functional importance of this association.
Insights
Autosomal dominant polycystic kidney disease (ADPKD) involves TRPP2 and PKD1 proteins. This study reveals the structural basis of their complex, identifying key interactions crucial for assembly and offering new avenues for ADPKD research.
Area of Science:
- Biochemistry
- Structural Biology
- Genetics
Background:
- Autosomal dominant polycystic kidney disease (ADPKD) is linked to mutations in TRPP2 and PKD1 genes.
- These genes encode proteins that form a critical ion channel/receptor complex.
Purpose of the Study:
- To elucidate the molecular structure of the TRPP2/PKD1 heterotetrameric complex.
- To understand the role of specific protein-protein interactions in ADPKD pathogenesis.
Main Methods:
- Computational modeling using a two-step docking strategy based on existing TRPP2 crystal structure.
- Site-directed mutagenesis and biochemical assays to identify and validate critical interface contacts.
Main Results:
- A novel di-trimer structural model of the TRPP2/PKD1 complex was generated.
- Key interface contacts between TRPP2 and PKD1 were identified and confirmed to be essential for complex assembly.
- Mutations disrupting these contacts impaired full-length complex formation in cellular models.
Conclusions:
- The study provides a detailed structural model of the TRPP2/PKD1 complex, revealing a unique di-trimer configuration.
- Identified critical interactions are essential for the assembly and stability of the functional complex.
- These findings offer a basis for developing strategies to modulate TRPP2-PKD1 association for future ADPKD research.
