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El ciclo del ácido tricarboxílico en las cianobacterias
1Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, USA.
Science (New York, N.Y.)
|December 17, 2011
Resumen
Las cianobacterias poseen una nueva vía para completar el ciclo del ácido tricarboxílico (TCA), compensando la ausencia de enzimas clave. Este hallazgo revela una flexibilidad metabólica previamente desconocida en estos microorganismos.
Área de la Ciencia:
- Microbiología Microbiología.
- La bioquímica es la bioquímica.
- Ingeniería Metabólica Ingeniería Metabólica.
Sus antecedentes:
- Se cree ampliamente que las cianobacterias poseen un ciclo incompleto de ácido tricarboxílico (TCA) debido a la ausencia de 2-oxoglutarato deshidrogenasa.
- Esta deficiencia enzimática impide la conversión directa del 2-oxoglutarato en la succinil-coenzima A (CoA).
Objetivo del estudio:
- Investigar las vías metabólicas en las cianobacterias que pueden compensar el ciclo TCA incompleto.
- Identificar nuevas enzimas y genes involucrados en rutas alternativas para la función del ciclo TCA en Synechococcus sp. El PCC 7002 también es un PCC.
Principales métodos:
- El análisis genómico de Synechococcus sp. PCC 7002 para identificar genes que codifican nuevas enzimas.
- Pruebas bioquímicas para confirmar la actividad enzimática de las proteínas identificadas.
- Genómica comparativa para determinar la distribución de estos genes en diferentes especies de cianobacterias y organismos relacionados.
Principales resultados:
- Identificación de genes que codifican una nueva descarboxilasa de 2-oxoglutarato y una deshidrogenasa de semialdehído succínico en Synechococcus sp. El PCC 7002 también es un PCC.
- Demostración de que estas dos enzimas colectivamente convierten el 2-oxoglutarato en succinato, reemplazando funcionalmente la 2-oxoglutarato deshidrogenasa y la succinil-CoA sintetasa.
- Estos genes están presentes en la mayoría de las cianobacterias, pero están ausentes en las especies de Prochlorococcus y Synechococcus marinos.
Conclusiones:
- Las cianobacterias poseen un ciclo funcional de TCA a través de una nueva vía enzimática, desafiando la creencia de larga data de su incompletud.
- Esta vía alternativa proporciona una estrategia metabólica para que las cianobacterias superen la falta de 2-oxoglutarato deshidrogenasa.
- La distribución de estos genes sugiere relaciones evolutivas potenciales y adaptaciones metabólicas en organismos procariotas.
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