PMID: 18512957

Authors:

Kuhnel K, Ke N, Cryle MJ, Sligar SG, Schuler MA, Schlichting I

Title:

Crystal Structures of Substrate-Free and Retinoic Acid-Bound Cyanobacterial Cytochrome P450 CYP120A1.

Journal:

Biochemistry. 2008 May 31.

Abstract:

The crystal structures of substrate-free and all- trans-retinoic acid-bound CYP120A1 from Synechocystis sp. PCC 6803 were determined at 2.4 and 2.1 A resolution, respectively, representing the first structural characterization of a cyanobacterial P450. Features of CYP120A1 not observed in other P450 structures include an aromatic ladder flanking the channel leading to the active site and a triple-glycine motif within SRS5. Using spectroscopic methods, CYP120A1 is shown to bind 13- cis-retinoic acid, 9- cis-retinoic acid, and retinal with high affinity and dissociation constants of less than 1 microM. Metabolism of retinoic acid by CYP120A1 suggests that CYP120A1 hydroxylates a variety of retinoid derivatives in vivo. On the basis of the retinoic acid-bound CYP120A1 crystal structure, we propose that either carbon 2 or the methyl groups (C16 or C17) of the beta-ionone ring are modified by CYP120A1.