6B86

2.2A Crystal Structure of Co-CAO1

Summary for 6B86

• Entry DOI: 10.2210/pdb6b86/pdb
• Descriptor: Carotenoid oxygenase 1, COBALT (II) ION (3 entities in total)
• Functional Keywords: beta-propeller, dioxygenase, oxidoreductase
• Biological source: Neurospora crassa (strain ATCC 24698 / 74-OR23-1A / CBS 708.71 / DSM 1257 / FGSC 987)
• Total number of polymer chains: 4
• Total formula weight: 238227.47

Authors

Hill, H.E.,Kiser, P.D. (deposition date: 2017-10-05, release date: 2018-07-04, Last modification date: 2023-10-04)

Primary citation

Sui, X.,Farquhar, E.R.,Hill, H.E.,von Lintig, J.,Shi, W.,Kiser, P.D.
Preparation and characterization of metal-substituted carotenoid cleavage oxygenases.
J. Biol. Inorg. Chem., 23:887-901, 2018

PubMed Abstract: Carotenoid cleavage oxygenases (CCO) are non-heme iron enzymes that catalyze oxidative cleavage of alkene bonds in carotenoid and stilbenoid substrates. Previously, we showed that the iron cofactor of CAO1, a resveratrol-cleaving member of this family, can be substituted with cobalt to yield a catalytically inert enzyme useful for trapping active site-bound stilbenoid substrates for structural characterization. Metal substitution may provide a general method for identifying the natural substrates for CCOs in addition to facilitating structural and biophysical characterization of CCO-carotenoid complexes under normal aerobic conditions. Here, we demonstrate the general applicability of cobalt substitution in a prototypical carotenoid cleaving CCO, apocarotenoid oxygenase (ACO) from Synechocystis. Among the non-native divalent metals investigated, cobalt was uniquely able to stably occupy the ACO metal binding site and inhibit catalysis. Analysis by X-ray crystallography and X-ray absorption spectroscopy demonstrate that the Co(II) forms of both ACO and CAO1 exhibit a close structural correspondence to the native Fe(II) enzyme forms. Hence, cobalt substitution is an effective strategy for generating catalytically inert but structurally intact forms of CCOs.

PubMed: 29946976
DOI: 10.1007/s00775-018-1586-0

Experimental method

X-RAY DIFFRACTION (2.2 Å)