Download MendeleyStructure and Spectroscopy of Alkene-Cleaving Dioxygenases Containing an Atypically Coordinated Non-Heme Iron Center.
Sui, X., Weitz, A.C., Farquhar, E.R., Badiee, M., Banerjee, S., von Lintig, J., Tochtrop, G.P., Palczewski, K., Hendrich, M.P., Kiser, P.D.(2017) Biochemistry 56: 2836-2852
- PubMed: 28493664 Search on PubMedSearch on PubMed Central
- DOI: https://doi.org/10.1021/acs.biochem.7b00251
- Primary Citation Related Structures:
5U8X, 5U8Y, 5U8Z, 5U90, 5U97 - PubMed Abstract:
Carotenoid cleavage oxygenases (CCOs) are non-heme iron enzymes that catalyze scission of alkene groups in carotenoids and stilbenoids to form biologically important products. CCOs possess a rare four-His iron center whose resting-state structure and interaction with substrates are incompletely understood. Here, we address this knowledge gap through a comprehensive structural and spectroscopic study of three phyletically diverse CCOs. The crystal structure of a fungal stilbenoid-cleaving CCO, CAO1, reveals strong similarity between its iron center and those of carotenoid-cleaving CCOs, but with a markedly different substrate-binding cleft. These enzymes all possess a five-coordinate high-spin Fe(II) center with resting-state Fe-His bond lengths of ∼2.15 Å. This ligand set generates an iron environment more electropositive than those of other non-heme iron dioxygenases as observed by Mössbauer isomer shifts. Dioxygen (O 2 ) does not coordinate iron in the absence of substrate. Substrates bind away (∼4.7 Å) from the iron and have little impact on its electronic structure, thus excluding coordination-triggered O 2 binding. However, substrate binding does perturb the spectral properties of CCO Fe-NO derivatives, indicating proximate organic substrate and O 2 -binding sites, which might influence Fe-O 2 interactions. Together, these data provide a robust description of the CCO iron center and its interactions with substrates and substrate mimetics that illuminates commonalities as well as subtle and profound structural differences within the CCO family.
- Department of Pharmacology, School of Medicine, Case Western Reserve University , 10900 Euclid Avenue, Cleveland, Ohio 44106, United States.
Organizational Affiliation:
