Investigating the effect of RXRa S427F mutant on RXRa tetramers

Abstract

Retinoid X nuclear receptors (RXRs) are ligand-dependent transcriptional modulators that execute their biological action through the generation of functional heterodimers. Biochemical data indicate that, in the absence of ligand, RXR can exist as an inactive tetramer and that its dissociation, induced by ligand, is important for receptor activation. When RXRa is freed from the tetramer, it forms heterodimers with obligated partners such as RAR, which are protective in cancer. The RXR-tetramer interface is assembled from amino acids that are conserved across several closely related receptors. A single point mutation on RXRa, S427F, which is found in 5% of patients with bladder cancer, is located exactly at the tetramerization interface; however its mechanism of action is unknown. To understand the effect of S427F mutation on the stability of the RXRa tetramer, we performed MD simulations.