Characterization of Four Bifunctional Plant IAM/PAM-Amidohydrolases Capable of Contributing to Auxin Biosynthesis
Beatriz Sánchez-Parra,
Henning Frerigmann,
Marta-Marina Pérez Alonso,
Víctor Carrasco Loba,
Ricarda Jost,
Mathias Hentrich,
Stephan Pollmann
Affiliations
Beatriz Sánchez-Parra
Center for Plant Biotechnology and Genomics (U.P.M.-I.N.I.A.), Technical University Madrid, Montegancedo Campus, Crta. M-40, km 38, 28223 Pozuelo de Alarcón (Madrid), Spain
Henning Frerigmann
Department of Plant Physiology, Faculty of Biology and Biotechnology, Ruhr-University Bochum, Universitätsstraße 150, 44801 Bochum, Germany
Marta-Marina Pérez Alonso
Center for Plant Biotechnology and Genomics (U.P.M.-I.N.I.A.), Technical University Madrid, Montegancedo Campus, Crta. M-40, km 38, 28223 Pozuelo de Alarcón (Madrid), Spain
Víctor Carrasco Loba
Center for Plant Biotechnology and Genomics (U.P.M.-I.N.I.A.), Technical University Madrid, Montegancedo Campus, Crta. M-40, km 38, 28223 Pozuelo de Alarcón (Madrid), Spain
Ricarda Jost
School of Plant Biology, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
Mathias Hentrich
Department of Plant Physiology, Faculty of Biology and Biotechnology, Ruhr-University Bochum, Universitätsstraße 150, 44801 Bochum, Germany
Stephan Pollmann
Center for Plant Biotechnology and Genomics (U.P.M.-I.N.I.A.), Technical University Madrid, Montegancedo Campus, Crta. M-40, km 38, 28223 Pozuelo de Alarcón (Madrid), Spain
Amidases [EC 3.5.1.4] capable of converting indole-3-acetamide (IAM) into the major plant growth hormone indole-3-acetic acid (IAA) are assumed to be involved in auxin de novo biosynthesis. With the emerging amount of genomics data, it was possible to identify over forty proteins with substantial homology to the already characterized amidases from Arabidopsis and tobacco. The observed high conservation of amidase-like proteins throughout the plant kingdom may suggest an important role of theses enzymes in plant development. Here, we report cloning and functional analysis of four, thus far, uncharacterized plant amidases from Oryza sativa, Sorghum bicolor, Medicago truncatula, and Populus trichocarpa. Intriguingly, we were able to demonstrate that the examined amidases are also capable of converting phenyl-2-acetamide (PAM) into phenyl-2-acetic acid (PAA), an auxin endogenous to several plant species including Arabidopsis. Furthermore, we compared the subcellular localization of the enzymes to that of Arabidopsis AMI1, providing further evidence for similar enzymatic functions. Our results point to the presence of a presumably conserved pathway of auxin biosynthesis via IAM, as amidases, both of monocot, and dicot origins, were analyzed.
