RESUMEN

The head protein of T4 bacteriophage requires the GroEL chaperonin for its insertion into a growing T4 head. Hundreds of thousands of copies of this protein must pass through the chaperonin in a limited time later in infection, indicating that the protein must use GroEL very efficiently and may contain sequences that bind tightly to GroEL. We show that green fluorescent protein (GFP) fused to the N terminus of the head protein can fold at temperatures higher than those at which the GFP protein can fold well by itself. We present evidence that this folding is promoted by the strong binding of N-terminal head protein sequences to GroEL. This binding is so strong that some fusion proteins can apparently deplete the cell of the GroEL needed for other cellular functions, altering the cellular membranes and slowing growth.

Asunto(s)

Bacteriófago T4/química , Chaperonina 60/metabolismo , Western Blotting , Electroforesis en Gel de Poliacrilamida , Escherichia coli/metabolismo , Genes Reporteros , Proteínas Fluorescentes Verdes/metabolismo , Modelos Genéticos , Plásmidos/metabolismo , Reacción en Cadena de la Polimerasa , Unión Proteica , Conformación Proteica , Desnaturalización Proteica , Pliegue de Proteína , Estructura Terciaria de Proteína , Proteínas Recombinantes de Fusión/metabolismo , Temperatura , Factores de Tiempo , Rayos Ultravioleta