Structural basis for independent origins of new catalytic machineries in plant AAAD proteins
Michael P. Torrens-Spence, Ying-Chih Chiang, Tyler Smith, Maria A. Vicent, Yi Wang, and Jing-Ke Weng
Received Date: 28th August 2018
A remarkable feature of rapidly evolving specialized metabolic systems is the origin of new catalytic machineries from progenitor enzymes catalyzing alternative reactions. Divergent evolution of the pyridoxal 5'-phosphate (PLP)-dependent aromatic amino acid decarboxylases (AAADs) in plants not only resulted in paralogous AAADs with specific substrate preference, but also repeatedly yielded evolutionarily new aldehyde synthases with additional oxidative deamination activity. The molecular mechanisms underlying such evolutionary development were unknown. Here, we report the structural and biochemical characterization of a number of functionally distinct plant AAAD-family enzymes. We resolve how independently evolved aldehyde synthases employ disparate molecular strategies to construct an aldehyde-producing catalytic machinery. This work highlights the pliability of an ancestral enzyme fold that furnishes access to new catalytic mechanisms with only a few mutations.
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This is an abstract of a preprint hosted on an independent third party site. It has not been peer reviewed but is currently under consideration at Nature Communications.