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Evolución y importancia metabólica del ciclo de la urea en las diatomeas fotosintéticas

Andrew E Allen¹, Christopher L Dupont, Miroslav Oborník

¹J. Craig Venter Institute, San Diego, California 92121, USA. aallen@jcvi.org

|May 13, 2011

Resumen

Las diatomeas utilizan un ciclo ornitina-urea derivado de exosimbiontes para recuperarse rápidamente de la limitación de nitrógeno. Esta vía, crucial para la productividad marina, enlaza genes bacterianos y de exosimbiontes para las funciones metabólicas esenciales.

Área de la Ciencia:

Biología marina Biología marina.
Biología molecular La biología molecular.
La bioquímica es la bioquímica.

Sus antecedentes:

Los diatomeas son el fitoplancton clave en las redes alimenticias marinas productivas.
Sus genomas contienen genes de bacterias, plástidos y huéspedes endosimbióticos secundarios (exosimbiontes).
La contribución metabólica de estos grupos de genes a las diatomeas sigue siendo en gran medida desconocida.

Objetivo del estudio:

Investigar el papel del ciclo ornitina-urea derivado de exosimbiontes en el metabolismo de las diatomeas.
Determinar su contribución a la utilización y recuperación del nitrógeno.
Explorar los vínculos metabólicos entre las vías derivadas de exosimbiontes, bacterias y huéspedes.

Principales métodos:

La interferencia del ARN (ARNi) para derribar la mitocondrial carbamoil fosfato sintasa.
Análisis metabolómicos para evaluar los niveles de metabolitos.
Genómica comparativa para comprender los orígenes de los genes.

Principales resultados:

El bloqueo de la carbamoil fosfato sintasa deterioró la respuesta de las diatomeas limitadas en nitrógeno a la adición de nitrógeno.
Los intermediarios del ciclo ornitina-urea se agotaron, vinculándolo a los ciclos de ácido tricarboxílico y glutamina sintetasa/glutamato sintetasa.
Los metabolitos, incluidos los precursores de prolina y poliamina, se generaron a través de vías acopladas de bacterias y exosimbiontes.

Conclusiones:

El ciclo ornitina-urea de las diatomeas facilita la recuperación rápida de la limitación de nitrógeno.
Actúa como un centro de distribución de carbono inorgánico y nitrógeno, esencial para el crecimiento de las diatomeas.
Este ciclo es vital para la contribución de las diatomeas a la productividad marina y la adaptación a la fluctuación de la disponibilidad de nutrientes.

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