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Las proteobacterias marinas metabolizan el glicolato a través del ciclo β-hidroxiaspartato
Lennart Schada von Borzyskowski1, Francesca Severi2, Karen Krüger3
1Department of Biochemistry & Synthetic Metabolism, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany. schada@mpi-marburg.mpg.de.
Nature
|November 15, 2019
Resumen
Las bacterias marinas asimilan el glicolato oceánico utilizando el ciclo β-hidroxiaspartato (BHAC). Esta vía eficiente, que involucra enzimas clave como una nueva imina reductasa, está distribuida globalmente y es crucial para el ciclo del carbono.
Área de la Ciencia:
- Microbiología marina
- Ciclos biogeoquímicos
- Las vías metabólicas
Sus antecedentes:
- El glicol es una fuente importante de carbono orgánico oceánico del fitoplancton.
- El destino del glioxilato, un metabolito del glicolato, en las bacterias marinas es poco conocido.
- El conocimiento previo carecía de vías eficientes para la asimilación de glioxilato.
Objetivo del estudio:
- Para aclarar la vía bioquímica para la asimilación de glioxilato en bacterias marinas.
- Determinar la estructura de las enzimas clave involucradas en esta vía.
- Evaluar la prevalencia y la actividad de esta vía en entornos marinos.
Principales métodos:
- Caracterización bioquímica del ciclo del β-hidroxiaspartato (BHAC).
- Análisis estructural de las enzimas BHAC, incluida una nueva imina reductasa.
- Análisis metagenómico marino para determinar la distribución y la abundancia de BHAC.
- Estudio de campo durante una floración de fitoplancton para medir la absorción de glicol y la expresión génica de BHAC.
Principales resultados:
- Las proteobacterias marinas asimilan el glyoxilato a través del BHAC, una vía de cuatro pasos que produce oxaloacetato.
- La BHAC es la vía de asimilación de glioxilato más eficiente conocida.
- BHAC se distribuye globalmente y es 20 veces más abundante que la vía del glicerato.
- Los genes BHAC se transcriben activamente durante la floración del fitoplancton, lo que indica una asimilación significativa del glicolato.
Conclusiones:
- El BHAC es una vía clave para que las bacterias marinas utilicen el glicolato derivado del fitoplancton.
- Esta vía representa un vínculo trófico significativo y no descrito previamente entre el fitoplancton y el bacterioplancton.
- La eficiencia y abundancia del BHAC resaltan su importancia en el ciclo del carbono oceánico.
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