Impact of the CYP27B1 p.R389H mutation on protein stability and function: implications for multiple sclerosis pathogenesis.

The CYP27B1 gene is crucial for vitamin D metabolism, which regulates immune functions. Mutations such as p.R389H may disrupt protein stability and function, potentially influencing diseases like multiple sclerosis (MS). This study examines the structural and functional consequences of the CYP27B1 p.R389H (rs118204009) mutation and its potential role in MS pathogenesis. The CYP27B1 sequence (UniProt ID: O15528) was retrieved, and its 3D structure was predicted using AlphaFold. The p.R389H mutation was introduced via PyMOL to assess structural and functional changes. Structural validation was conducted using ERRAT2, VERIFY3D, and Ramachandran plot analysis. Stability was analyzed using I-Mutant, Mcsm, DDGun, DynaMut, and Mupro, while functional impact was predicted with PolyPhen-2, PhD-SNP, SNPs&GO, and SIFT. Evolutionary conservation was assessed with ConSurf. AlphaFold predicted a high-confidence 3D structure of CYP27B1 (pLDDT > 90), highlighting the p.R389H mutation, where arginine is substituted by histidine. Structural validation showed minimal disruption, while phylogenetic analysis identified the mutation's location in a conserved region, highlighting its potential functional significance. Stability analysis predicted a destabilizing effect (ΔΔG values ranging from - 0.3 to - 2.038 kcal/mol), and functional impact tools classified the mutation as "probably damaging" and disease-associated. Molecular dynamics simulations further supported these results by revealing altered structural behavior of the mutant protein, with reduced flexibility and stability. Computational findings suggested p.R389H (rs118204009) mutation could impair the role of CYP27B1 in vitamin D metabolism, potentially contributing to MS pathogenesis.