Structural analysis of CYP2R1 in complex with vitamin D3

Area of Science:

• Biochemistry
• Molecular Biology
• Enzymology

Background:

• Vitamin D activation to its hormonal form involves cytochrome P450 enzymes.
• CYP2R1 is crucial for the initial hydroxylation of vitamin D to 25-hydroxyvitamin D.
• Mutations in CYP2R1 lead to inherited rickets due to vitamin D 25-hydroxylase deficiency.

Purpose of the Study:

• To elucidate the structural basis of CYP2R1's substrate specificity.
• To understand the molecular mechanisms underlying inherited rickets caused by CYP2R1 deficiency.

Main Methods:

• Purification of the CYP2R1 hemeprotein.
• Confirmation of vitamin D 25-hydroxylase activity.
• X-ray crystallography of CYP2R1 in complex with vitamin D3.

Main Results:

• The crystal structure of CYP2R1 with vitamin D3 was determined.
• CYP2R1 adopts a closed conformation with a specific substrate access channel.
• Vitamin D3 binds in an extended conformation within the active site, interacting with hydrophobic residues.

Conclusions:

• The determined structure reveals the secosteroid binding mode in CYP2R1.
• The findings provide a molecular rationale for inherited rickets associated with CYP2R1 mutations.
• Understanding CYP2R1 structure is key to addressing vitamin D metabolism disorders.