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bioRxiv · 10.1101/834747

Allosteric deregulation of phenylalanine biosynthesis evolved with the emergence of vascular plants

El-Azaz, J.·Canovas, F. M.·Barcelona, B.·Avila, C.·de la Torre, F. N.
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Abstract

Phenylalanine (Phe) is the precursor of essential secondary products in plants. Here we show that a key, rate-limiting step in Phe biosynthesis, which is catalyzed by arogenate dehydratase (ADT), experienced allosteric de-regulation during evolution. Enzymes from microorganisms and type-I ADTs from plants are strongly feedback-inhibited by Phe, while type-II isoforms remain active at high levels of Phe. We have found that type-II ADTs are widespread across seed plants and their overproduction resulted in a dramatic accumulation of Phe in planta, up to 40-times higher than those observed following the expression of type-I enzymes. Punctual changes in the allosteric binding site of Phe and adjacent region are responsible for the observed relaxed regulation. The phylogeny of plant ADTs evidences that the emergence of type-II isoforms with relaxed regulation occurred at some point in the transition between non-vascular plants and tracheophytes enabling the massive production of Phe-derived compounds, primarily lignin, which are attributes of vascular plants.

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El-Azaz, J., Canovas, F. M., Barcelona, B., Avila, C., de la Torre, F. N.. 2019-11-08. Allosteric deregulation of phenylalanine biosynthesis evolved with the emergence of vascular plants. https://doi.org/10.1101/834747

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