Publications
The Journal of biological chemistryJan 2023 |
105161
DOI:
10.1016/j.jbc.2023.105161

Novel exported fusion enzymes with chorismate mutase and cyclohexadienyl dehydratase activity: shikimate pathway enzymes teamed up in no man's land

Stocker, Christian; Khatanbaatar, Tamjidmaa; Bressan, Luca; Würth-Roderer, Kathrin; Cordara, Gabriele; Krengel, Ute; Kast, Peter
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Abstract
Chorismate mutase (CM) and cyclohexadienyl dehydratase (CDT) catalyze two subsequent reactions in the intracellular biosynthesis of l-phenylalanine (Phe). Here, we report the discovery of novel and extremely rare bifunctional fusion enzymes, consisting of fused CM and CDT domains, which are exported from the cytoplasm. Such enzymes were found in only nine bacterial species belonging to non-pathogenic γ- or β-Proteobacteria. In γ-proteobacterial fusion enzymes, the CM domain is N-terminal to the CDT domain, whereas in β-Proteobacteria the order is inverted. The CM domains share 15-20% sequence identity with the AroQγ class CM holotype of Mycobacterium tuberculosis (*MtCM), and the CDT domains 40-60% identity with the exported monofunctional enzyme of Pseudomonas aeruginosa (PheC). In vitro kinetics revealed a Km
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