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Estructura cristalina del transportador de nitrato de doble afinidad de la planta NRT1.1
Ji Sun1, John R Bankston2, Jian Payandeh3
1Department of Pharmacology, Box 357280, University of Washington, Seattle, Washington 98195, USA.
Nature
|February 28, 2014
Resumen
El transportador de nitrato de Arabidopsis NRT1.1 funciona como un dímero, cambiando entre estados de baja y alta afinidad. La fosforilación en Thr101 controla esta dimerización, lo que permite la absorción de nitrato de doble modo, crucial para el crecimiento de las plantas.
Área de la Ciencia:
- Biología Vegetal Biología Vegetal Biología Vegetal
- Biología Molecular Biología Molecular
- La bioquímica es la bioquímica.
Sus antecedentes:
- El nitrato es esencial para el crecimiento de las plantas, pero las concentraciones en el suelo varían ampliamente.
- Arabidopsis NRT1.1 es un transportador de nitrato de doble afinidad, pero su mecanismo sigue sin estar claro.
- La modificación post-traducional, específicamente la fosforilación de Thr101, regula la actividad de NRT1.1.
Objetivo del estudio:
- Para aclarar el mecanismo estructural y molecular del transporte de doble afinidad de NRT1.1.
- Para entender cómo la fosforilación de Thr101 controla la actividad del transportador y los estados de afinidad.
- Para investigar el papel de la dimerización en la función NRT1.1.
Principales métodos:
- Cristalografía de rayos X para determinar la estructura de NRT1.1.1. sin fosforilación.
- Ensayo de transferencia de energía de resonancia de fluorescencia basado en células (FRET) para estudiar la dimerización en membranas.
- Mutagenesis dirigida al sitio (mutación fosfomimética de Thr101).
- Análisis del túnel de transporte del sustrato.
Principales resultados:
- La estructura cristalina reveló que el NRT1.1 no fosforilado forma un homodímero orientado hacia adentro.
- El sitio de fosforilación de Thr101 se encuentra cerca de la interfaz del dímero, vinculando la fosforilación al estado oligomérico.
- La NRT1.1 funcional se dimeriza en la membrana celular.
- Una mutación fosfomimética en Thr101 interrumpe la dimerización, dando como resultado un transportador de alta afinidad.
Conclusiones:
- NRT1.1 utiliza un interruptor de dimerización controlado por fosforilación para la absorción de nitrato de doble afinidad.
- Este mecanismo permite a las plantas adaptar la absorción de nitratos a través de una amplia gama de concentraciones en el suelo.
- Las ideas estructurales en NRT1.1 proporcionan una base molecular para la regulación del transportador de nutrientes.
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