6BIG

Crystal structure of cobalt-substituted Synechocystis ACO

Summary for 6BIG

• Entry DOI: 10.2210/pdb6big/pdb
• Related: 6B86
• Descriptor: Apocarotenoid-15,15'-oxygenase, COBALT (II) ION, CHLORIDE ION, ... (4 entities in total)
• Functional Keywords: dioxygenase, cobalt, non-heme iron, beta propeller, oxidoreductase
• Biological source: Synechocystis sp. (strain PCC 6803 / Kazusa)
• Total number of polymer chains: 4
• Total formula weight: 217718.85

Authors

Sui, X.,Shi, W.,Kiser, P.D. (deposition date: 2017-11-02, 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 (2.21 Å)