Did α-Synuclein and Glucocerebrosidase Coevolve? Implications for Parkinson's Disease

Mutations in the GBA1 gene are associated with increased risk of Parkinson's disease, and the protein produced by the gene, glucocerebrosidase, interacts with alpha-synuclein, the protein at the center of the disease etiology. One possibility is that the mutations disrupt a beneficial interaction between the proteins, and a beneficial interaction would imply that the proteins have coevolved. To explore this possibility, a correlated mutation analysis has been performed for all 72 vertebrate species where complete sequences of alpha-synuclein and glucocerebrosidase are known. The most highly correlated pair of residue variations is alpha-synuclein A53T and glucocerebrosidase G115E. Intriguingly, the A53T mutation is a Parkinson's disease risk factor in humans, suggesting the pathology associated with this mutation and interaction with glucocerebrosidase might be connected. Correlations with beta-synuclein are also evaluated. To assess the impact of lowered species number on accuracy, intra and inter-chain correlations are also calculated for hemoglobin, using mutual information Z-value and direct coupling analyses.