RESUMEN
The UbiB protein kinase-like (PKL) family is widespread, comprising one-quarter of microbial PKLs and five human homologs, yet its biochemical activities remain obscure. COQ8A (ADCK3) is a mammalian UbiB protein associated with ubiquinone (CoQ) biosynthesis and an ataxia (ARCA2) through unclear means. We show that mice lacking COQ8A develop a slowly progressive cerebellar ataxia linked to Purkinje cell dysfunction and mild exercise intolerance, recapitulating ARCA2. Interspecies biochemical analyses show that COQ8A and yeast Coq8p specifically stabilize a CoQ biosynthesis complex through unorthodox PKL functions. Although COQ8 was predicted to be a protein kinase, we demonstrate that it lacks canonical protein kinase activity in trans. Instead, COQ8 has ATPase activity and interacts with lipid CoQ intermediates, functions that are likely conserved across all domains of life. Collectively, our results lend insight into the molecular activities of the ancient UbiB family and elucidate the biochemical underpinnings of a human disease.
Asunto(s)
Conducta Animal , Ataxia Cerebelosa/enzimología , Cerebelo/enzimología , Proteínas Mitocondriales/deficiencia , Músculo Esquelético/enzimología , Ubiquinona/deficiencia , Animales , Células COS , Ataxia Cerebelosa/genética , Ataxia Cerebelosa/fisiopatología , Ataxia Cerebelosa/psicología , Cerebelo/fisiopatología , Cerebelo/ultraestructura , Chlorocebus aethiops , Modelos Animales de Enfermedad , Tolerancia al Ejercicio , Femenino , Predisposición Genética a la Enfermedad , Células HEK293 , Humanos , Metabolismo de los Lípidos , Masculino , Aprendizaje por Laberinto , Ratones Endogámicos C57BL , Ratones Noqueados , Proteínas Mitocondriales/química , Proteínas Mitocondriales/genética , Modelos Moleculares , Actividad Motora , Fuerza Muscular , Músculo Esquelético/fisiopatología , Fenotipo , Unión Proteica , Conformación Proteica , Proteómica/métodos , Reconocimiento en Psicología , Prueba de Desempeño de Rotación con Aceleración Constante , Saccharomyces cerevisiae/enzimología , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Convulsiones/enzimología , Convulsiones/genética , Convulsiones/fisiopatología , Relación Estructura-Actividad , Factores de Tiempo , Transfección , Ubiquinona/química , Ubiquinona/genéticaRESUMEN
Coenzyme Q (Q) is an electron transporter in the respiratory chain and a lipid-soluble antioxidant that decreases in humans with age. Here we show that 4-nitrobenzoate inhibited 4-hydroxybenzoate:polyprenyl transferase (Coq2) in a competitive manner and dose-dependently decreased Q in mammalian cells without accumulation of Q intermediates. As 4-nitrobenzoate neither interfered with mitochondrial respiration nor induced oxidative stress, it should prove a valuable tool for studies on both Q deficiency and Q supplementation.