Structure Bioinformatics of Six Human Integral Transmembrane Enzymes and their AlphaFold3 Predicted Water-Soluble QTY Analogs: Insights into FACE1 and STEA4 Binding Mechanisms.

Objective: Human integral membrane enzymes are essential for catalyzing a wide range of biochemical reactions and regulating key cellular processes. However, studying these enzymes remains challenging due to their hydrophobic nature, which necessitates the use of detergents. This study explores whether applying the QTY code can reduce the hydrophobicity of these enzymes while preserving their structures and functions, thus facilitating bioinformatics analysis of six key integral membrane enzymes: MGST2, LTC4S, PTGES, FACE1, STEA4, and SCD.

Methods: The water-soluble QTY analogs of the six membrane enzymes were predicted using AlphaFold3. The predicted structures were superposed with CyroEM determined native structures in PyMOL to observe changes in structure and protein-ligand binding ability.

Results: The native membrane enzymes superposed well with their respective QTY analogs, with the root mean square deviation (RMSD) ranging from 0.273 Å to 0.875 Å. Surface hydrophobic patches on the QTY analogs were significantly reduced. Importantly, the protein-ligand interactions in FACE1 and STEA4 were largely preserved, indicating maintained functionality.

Conclusion: Our structural bioinformatics studies using the QTY code and AlphaFold3 not only provide the opportunities of designing more water-soluble integral membrane enzymes, but also use these water-soluble QTY analogs as antigens for therapeutic monoclonal antibody discovery to specifically target the key integral membrane enzymes.