Abstract 1768: Biochemical and structural analysis of the Neurofibromin (NF1) protein and a potential role for protein destabilization in Rasopathy diseases

Abstract

Abstract Neurofibromin is the 320 kilodalton protein product of the NF1 gene which is mutated in the Rasopathy disease Neurofibromatosis Type I. Defects in NF1 lead to abrogation of the GTPase activating activity of the protein, leading to aberrant signaling through the RAS-MAPK pathway. Very little is known about the function of the majority of the NF1 protein—to date only the GAP domain and a region containing a Sec-PH motif have detailed structural information. To better understand the role of this large protein, we have carried out a series of biochemical and biophysical studies which clearly show that full length NF1 protein exists primarily as a dimer. Data from in vivo experiments confirmed that this dimerization also occurs in cells, and presumably has biological implications. A model was generated from negative-stain EM data which suggests that NF1 monomers form both intermolecular contacts to form dimers and intramolecular contacts which stabilize the individual monomers. Deletion analysis permitted us to map these two interacting domains to different parts of the NF1 protein, and crosslinking studies coupled with mass spectrometry helped to identify regions of possible interaction. In addition, introduction of point mutations observed in patients with NF diseases caused a dramatic decrease in the stability of proteins both in vitro and in vivo, potentially arguing for a rationale for loss of NF1 activity by these single mutations Citation Format: Mukul Sherekar, Sae-Won Han, Simon Messing, Matthew Drew, William Gillette, Claire Lorenzo, Frank McCormick, Dominic Esposito. Biochemical and structural analysis of the Neurofibromin (NF1) protein and a potential role for protein destabilization in Rasopathy diseases [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1768.