Decoding PDI diversity: insights into structure, domains, and functionality in sorghum

Abstract

Proteins play indispensable roles in cellular function, acting as both structural components and catalysts for essential biological processes. Their proper folding into three-dimensional structures is critical for functionality. To ensure correct folding, proteins interact with chaperones and folding catalysts such as Protein Disulfide Isomerases (PDIs), which assist in the formation and rearrangement of disulfide bonds that stabilize proteins by linking cysteine residues. PDIs are part of the thioredoxin (TRX) superfamily and are characterized by a conserved CXXC motif that contributes to their redox potential. They exhibit isomerase and oxidoreductase activities, that enable them to rearrange and form new disulfide bonds. PDI family members in sorghum (SbPDI) present a broad and largely unexplored diversity in domain order, structure, and architecture between or even within species. To shed light on this diversity, we identified and characterized PDI family members in sorghum in silico to explore their domain architecture, three-dimensional structure and functionality. Author summaryIn this work, we explore how genomic and molecular tools can improve our understanding of the function and diversity of the protein disulfide isomerase (PDI) family in plants, using sorghum as a model and humans as a reference. By analysing domain architecture and predicted structures across the PDI family, we lay the groundwork for future studies investigating their roles in plant development and stress responses, including through targeted gene editing approaches. Although PDIs have been widely studied in humans, their structural and functional diversity in plants remains largely unexplored. With this study, I aim to help close this knowledge gap and highlight the structural differences of PDIs in plants.