Identificación de determinantes estructurales de la activación de los receptores de ácido abscísico (ABA)

Fernández-Giro Muñoz, Miriam (2021). Identificación de determinantes estructurales de la activación de los receptores de ácido abscísico (ABA). Proyecto Fin de Carrera / Trabajo Fin de Grado, E.T.S. de Ingeniería Agronómica, Alimentaria y de Biosistemas (UPM), Madrid.

Description

Title: Identificación de determinantes estructurales de la activación de los receptores de ácido abscísico (ABA)
Author/s:
  • Fernández-Giro Muñoz, Miriam
Contributor/s:
  • Albert de la Cruz, Armando
  • Fernández Pacios, Luis
Item Type: Final Project
Degree: Grado en Biotecnología
Date: June 2021
Subjects:
Faculty: E.T.S. de Ingeniería Agronómica, Alimentaria y de Biosistemas (UPM)
Department: Biotecnología - Biología Vegetal
Creative Commons Licenses: Recognition - No derivative works - Non commercial

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Abstract

Abscisic acid (ABA) is the main phytohormone involved in adaptive responses to abiotic stress, such as drought or salinity. ABA is a sesquiterpene which can be found in various species across different kingdoms, including bacteria, fungi and animals. In vascular plants, ABA is produced under water stress in vegetative tissues and controls the closure of stomata as well as gene expression associated to drought tolerance. ABA receptors comprise a large family of proteins known as PYR (PYRABACTIN RESISTANCE), PYL (PYR1-LIKE) and RCAR (REGULATORY COMPONENTS OF ABA RECEPTORS). All of them belong to the superfamily of START/Bet v proteins, whose members are characterized by the presence of a cavity able to accommodate hydrophobic ligands. Upon ABA binding, PYLs undergo a conformational change in two key loops (named gate and latch) in the binding site that leads to dimer dissociation and interaction with a clade of protein phosphatases 2C family, which acts as a co-receptor. The ternary complex ABA-receptor-co-receptor causes PP2C inactivation due to the blocking of the active site, which initiates the downstream signaling mediated by a subclass III SnRK2. Recently, a new ancestral ABA receptor has been found in the hepatic plant Marchantia polymorpha that shows certain ABA-independent activity. However, the inhibition of PP2C is enhanced in the presence of ABA. Besides, the algal PYL-homolog encoded by Zygnema circumcarinatum was reported to have basal, ligand-independent activity of PP2C repression, suggesting this to be an ancestral function. Identifying the structural determinants in the activation could be of huge benefit in order to design an enhanced receptor for reducing the water use in big croplands, by preventing water loss in plants. For that goal, the properties of three ABA receptors have been analyzed and compared. In the wild-type Solanum lycopersicum SlPYL1, a dimeric receptor present in tomato plants, a point mutation was introduced in one of the key residues in the latch loop. The objective was to resemble the sequence shown by the monomeric receptors. Hence, in this work, a combination of computational and experimental approaches was used to characterize the three ABA receptors: SlPYL1 wild-type, SlPYL1 mutant E151D and MpPYL1. The structure of the three receptors was solved using X-ray crystallography. The analysis will provide insight on the molecular bases for ABA-mediated activation. Our results show that the three receptors bind ABA and can inhibit PP2C activity. The mutant receptor has shown the expected effects in interacting with ABA and inhibiting the PP2C with a similar affinity than the wild-type. In turn, MpPYL1 has shown particular properties which are discussed in the thesis.

More information

Item ID: 69283
DC Identifier: https://oa.upm.es/69283/
OAI Identifier: oai:oa.upm.es:69283
Deposited by: Biblioteca ETSI Agrónomos
Deposited on: 15 Dec 2021 10:36
Last Modified: 15 Feb 2022 23:30
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