Year: 2025
Type: article
Abstract: PrnB, a long-standing member of the recently reclassified heme-dependent aromatic oxygenase (HDAO) superfamily of histidine-ligated heme enzymes, catalyzes the conversion of 7-chloro- l -tryptophan (7-Cl-Trp) to monodechloroaminopyrrolnitrin (MCAP). This unique ring rearrangement is an essential step in the biosynthesis of the broad-spectrum antifungal pyrrolnitrin. The conversion of 7-Cl-Trp to MCAP by PrnB differs from other HDAOs, which typically affect the mono- or dioxygenation of aromatic substrates. However, the molecular basis for this transformation has remained enigmatic due to the inability to reconstitute enzymatic activity in vitro . Transient kinetic approaches reveal that the sequential binding of 7-Cl-Trp and dioxygen results in the formation of a long-lived oxy-ferrous complex. Despite similarity to intermediates found in other HDAOs, the PrnB-oxy ternary species does not react with bound 7-Cl-Trp. However, the provision of a surrogate redox delivery system supports turnover, and single-turnover studies reveal that activation of the oxy-complex is required. Together, these studies reveal the molecular basis for functional expansion of the HDAO structural framework through alteration of the strategy of oxygen activation.
Source: Biochemistry
Authors: R. Brian McMillan, Hannah E. Gering, Anastasia E. Ledinina, Shan Xue, Sayali Karandikar, Shuangjun Lin, Garim You, Tzu-Yu Chen, Yisong Guo, Wei-chen Chang, Thomas M. Makris
Language: English
Subfield: Inorganic Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: green
Awards: G1410756938, G2889594291, G3381096136, G4562723449, G5496315722, G9000044403, Understanding How Nonheme Iron-Dependent Enzymes Assemble Pharmacophores: Studies of Cyclopropane, Aziridine, and Isonitrile Formation, Dissect Mechanism of Iron(II)/2-Oxoglutarate Dependent Enzymes Catalyzed Halogenation in Nucleotide Biosynthesis
OpenAlex ID: W4413304170