6on1

Publication Abstract from PubMed

Extradiol dioxygenases are essential biocatalysts to breakdown catechols. The vicinal oxygen chelate (VOC) superfamily contains a large number of extradiol dioxygenases, most of which are found as part of catabolic pathways degrading a variety of natural and human-made aromatic rings. However, the VOC also contains an emerging class of biosynthetic dioxygenases. The L-3,4-dihydroxyphenylalanine (L-DOPA) extradiol dioxygenases are from pathways to various antibacterial or antitumor natural products, and their structural features are anticipated to be distinct from other VOC extradiol dioxygenases. Herein, we identified a new L-DOPA dioxygenase from the thermophilic bacterium Streptomyces sclerotialus (SsDDO), through a sequence and genome context analysis. The activity of SsDDO was kinetically characterized with L-DOPA using a UV-vis spectrophotometer and an oxygen electrode. The optimal temperature of the assay was 55 C, at which the Km and kcat of SsDDO were 110 +/- 10 muM and 2.0 +/- 0.1 s-1, respectively. We determined the de novo crystal structures of SsDDO in both the ligand-free form and as a substrate-bound complex, refined to 1.99 A and 2.31 A resolution, respectively. These structures reveal that SsDDO possesses a Form IV arrangement of betaalphabetabetabeta modules, the first characterization of this assembly from among the VOC/Type I extradiol dioxygenase protein family. EPR spectra of Fe-NO adducts for the resting and substrate-bound enzyme were obtained. This work contributes to our understanding of a growing class of topologically distinct VOC dioxygenases, and the obtained structural features will expand our knowledge of the extradiol cleavage reaction within the VOC superfamily.

Crystal Structures of L-DOPA Dioxygenase from Streptomyces Sclerotialus.,Wang Y, Shin I, Fu Y, Colabroy KL, Liu A Biochemistry. 2019 Jun 10. doi: 10.1021/acs.biochem.9b00396. PMID:31180203^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.