Abstract: SA-OR062

Modeling the Structural and Dynamical Changes of TRPV5 Caused by the A563T Variation Based on the Structure of TRPV6

Session Information

Category: Fluid, Electrolytes, and Acid-Base

  • 704 Fluid, Electrolyte, Acid-Base Disorders

Authors

  • Wang, Lingyun, University of Alabama at Birmingham , Birmingham, Alabama, United States
  • Peng, Ji-Bin, University of Alabama at Birmingham , Birmingham, Alabama, United States
Background

TRPV5 is an epithelial Ca2+ channel that plays a key role in the active Ca2+ reabsorption process in the kidney. The single nucleotide polymorphism (SNP) rs4252499 in TRPV5 gene has a minor allele frequency of around 0.17 in African descendants. This SNP results in an A563T variation in the sixth transmembrane (TM) domain of TRPV5. Our previous study indicates that the variation increases Ca2+ uptake and alters Mg2+ sensitivity of TRPV5. To understand the molecular mechanism, molecular simulations have been performed based on the structure of TRPV1. Recently, the structure of TRPV6 was determined. Since TRPV5 is much more similar to TRPV6 than TRPV1, new molecular simulation based on TRPV6 structure would provide more accurate information on the A563T variation in TRPV5.

Methods

Using MODELLER, TRPV5 model was set up based on a newly deposited structure of TRPV6 which shares 75% amino acid identity with TRPV5. This model contains all the six TM helices and the TRP domain of TRPV5. The A563T variation was introduced into TRPV5 using PyMOL. To mimic the membrane environment, the modeled TRPV5 was embedded in a lipid bilayer composed of 299 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) lipids using CHARMM-GUI, and then water molecules were added on both sides of the bilayer. Two 400 ns molecular dynamic simulations were performed using AMBER14.

Results

Consistent with TRPV1-based simulation, the current simulation indicates that the A563T variation results in increased contacts between residues 563 and V540, enhanced stability for the secondary structure of TM helix 6, and reduced correlated motion among monomers. The stable secondary structure of the variant mainly results from the stabilized hydrogen bond between T563 and T567. In contrast to TRPV1-based simulation, no significant changes in the pore size or in the electrostatic potential for the pore region were observed between the two forms of TRPV5 in this study.

Conclusion

Simulations based on the newly determined TRPV6 structure confirm that the A563T variation affects the structure and dynamics of TRPV5 through increased interactions with V540, which is one residue away from the key residue D542 in the Ca2+ filter.

Funding

  • NIDDK Support