Deregulation of phenylalanine biosynthesis evolved with the emergence of vascular plants. Issue 1 (27th September 2021)

• Record Type: Journal Article
• Authors: El-Azaz, Jorge; Cánovas, Francisco M; Barcelona, Belén; Ávila, Concepción; de la Torre, Fernando
• Is Part Of: Plant physiology. Volume 188:Issue 1(2022)
• Page Start: 134
• Page End: 150
• Publication Date: 2021-09-27
• Subjects: Plant physiology -- Periodicals; Botany -- Periodicals; Periodicals; Electronic journals; 571.2
• DOI: 10.1093/plphys/kiab454
• Languages: English
• ISSNs: 0032-0889

Abstract

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, experienced feedback 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, reaching levels 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 nonvascular plants and tracheophytes, enabling the massive production of Phe-derived compounds, primarily lignin, a hallmark of vascular plants. Abstract : The appearance of arogenate dehydratase isoenzymes with reduced feedback inhibition during the early evolution of plants enabled the massive biosynthesis of phenylalanine-derived compounds.