Expanding the Alkene‐Forming Capability of the Pseudomonas Savastanoi Ethylene‐Forming Enzyme

ABSTRACT Ethylene is an established signaling molecule in plants and other organisms; however, the biosynthesis and biological roles of gaseous alkenes other than ethylene are less well defined. The Pseudomonas savastanoi ethylene/succinate‐forming enzyme (PsEFE) catalyzes ethylene production from 2‐oxoglutarate (2OG), though does not catalyze formation of alkenes from C4 alkyl‐ or hydroxyl‐substituted 2OG derivatives. Here we report studies on the reactivity of L206 PsEFE variants with C4‐substituted 2OG derivatives. Spectroscopic evidence reveals that L206V and L206A PsEFE react with C4‐substituted 2OG derivatives to give diacid and alcohol products, similarly to wildtype (wt) PsEFE. Importantly, L206V PsEFE, but not L206A and L206G PsEFE, catalyzed production of low levels of acetaldehyde and propylene from the natural metabolites 4‐hydroxy‐2OG and 4‐methyl‐2OG, respectively. By contrast, L206A PsEFE, but not L206V and L206G PsEFE, catalyzed formation of low levels of 1‐butylene from 4‐ethyl‐2OG. Together with studies from others, the combined results indicate the potential of bump‐and‐hole studies to modify the substrate and product selectivities of PsEFE reactions, provided that the PsEFE variant:2OG derivative pairs are matched. The results suggest that wildtype 2OG oxygenases other than PsEFE may catalyze production of gaseous alkenes other than ethylene.