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La flavoproteína especializada promueve la migración de azufre y la formación de espiroaminas en la biosíntesis de

Yuta Tsunematsu^1,2, Naoya Maeda¹, Michio Sato¹

¹Department of Pharmaceutical Sciences, University of Shizuoka, Shizuoka 422-8526, Japan.

Journal of the American Chemical Society

|December 22, 2020

Resumen

Los investigadores descubrieron una nueva enzima, AclR, que crea puentes de disulfuro inusuales en las epididiodicetopiperazinas (ETP). Esta enzima

Área de la Ciencia:

La bioquímica
Micología
Biología Química

Sus antecedentes:

Las epididiodicetopiperazinas (ETP) son ciclodipéptidos de importancia ecológica y medicinal.
El aspiroclorino, un ETP tóxico de Aspergillus oryzae, tiene un andamio inusual con un puente de disulfuro anillado y un sistema espiroaminal.
Anteriormente no se conocía la base bioquímica de esta desviación estructural en las ETP.

Objetivo del estudio:

Elucidar el mecanismo bioquímico detrás de la formación del andamio ETP aberrante en la aspiroclora.
Identificar la enzima responsable de la migración única de enlaces carbono-azufre y la formación de anillos espiro.
Comprender el papel de la acetilación en la biosíntesis de estas moléculas complejas.

Principales métodos:

Cribado genético en Aspergillus oryzae para identificar los genes candidatos.
Construcción y análisis de un mutante con deficiencia de ACIR.
Ensayos enzimáticos in vitro para determinar la actividad catalítica del AclR.
Análisis cristalográfico y mutacional de la AclR.
Análisis bioinformático para identificar grupos de genes fúngicos relacionados.

Principales resultados:

Descubrimiento de una nueva oxidorreductaza, AclR, que cataliza la migración de enlaces carbono-azufre y la formación de anillos espiro.
Identificación de un paso críptico de acetilación como requisito previo para el reordenamiento.
Demostración de que AclR por sí solo promueve la migración de sulfamilo, la eliminación del grupo acetoxi y la formación de espiroaminas.
Caracterización del pliegue de la tiorredoxina oxidoreductasa de AclR con un motivo CXXH no canónico, distinto de las oxidasas ETP típicas.
Se encontró que el dinucleótido de flavin-adenina (FAD) apoya el plegamiento de proteínas, no actúa como un cofactor redox.
AclR sirve como un mango de bioinformática para descubrir grupos de genes para ETPs relacionados.

Conclusiones:

AclR es la primera enzima identificada capaz de catalizar tanto la migración de enlaces carbono- azufre como la formación de anillos espiro en la biosíntesis de ETP.
La vía ACL incluye un paso críptico de acetilación.
AclR representa una enzima especializada de la familia de la tiorredoxina oxidoreductasa que amplía la diversidad química de las ETP.
Este descubrimiento proporciona información sobre la biosíntesis de productos naturales complejos con farmacóforos disulfuro aberrantes.

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