Impact of ALS-linked Mutations on the Structure and Dynamics of Profilin-1

Abstract

Dysregulation of proteins involved in the formation and maintenance of the actin cytoskeleton has been implicated in neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS). Mutations in the actin-binding protein, profilin-1 (PFN1), have been identified and linked to familial ALS. PFN1 is an essential protein that regulates different cellular processes, including membrane trafficking, neurite outgrowth, axonal development, neuronal growth cone formation, and GTPase signaling. Recent studies have shown that different ALS-linked PFN1 mutations can lead to either a gain or loss of function, depending on the stability of the mutant and its propensity for aggregation. In this thesis, I focused on two ALS-linked variants- G118V and M114T which exhibit a gain of function in formin-mediated actin dynamics. To understand the biophysical differences between these two mutants and WT PFN1, I investigated how these mutations impact PFN1 binding affinity to its ligands using fluorescence and NMR spectroscopic methods. Reduced chemical shift perturbations observed in the β-strand containing the mutation site in M114T PFN1, compared to WT PFN1 suggest that the mutation impacts allosteric communication. In addition, I characterized the effects of the M114T mutation on PFN1 dynamics across fast and slow time scales. This dissertation represents the first study to examine conformational dynamics changes in ALS-linked PFN1 variants, providing insights into their functional impact and elucidating the role of cytoskeletal perturbation in disease.Biochemistry and Molecular Biotechnology2 years2027-05-2