RESUMEN
Vaccinia virus A46 is an anti-inflammatory and non-anti-apoptotic, two-domain member of the poxviral Bcl-2-like protein family that inhibits the cellular innate immune response at the level of the Toll/interleukin-1 receptor (TIR) domain-containing TLR adaptor proteins MAL, MyD88, TRAM, and TRIF. The mechanism of interaction of A46 with its targets has remained unclear. The TIR domains of MAL and MyD88 have been shown to signal by forming filamentous assemblies. We show a clear concentration-dependent destruction of both of these assemblies by A46 by means of negative-stain electron microscopy from molar ratios of 1:15 for MAL and 1:30 for MyD88. Using targeted mutagenesis and protein-protein crosslinking, we show that A46 interacts with MAL and MyD88 through several facets, including residues on helices α1 and α7 and the C-terminal flexible region. We propose a model in which A46 targets the MAL and MyD88 signalosome intra-strand interfaces and gradually destroys their assemblies in a concentration-dependent manner.
Asunto(s)
Proteínas Proteolipídicas Asociadas a Mielina y Linfocito/química , Factor 88 de Diferenciación Mieloide/química , Proteínas Virales/química , Sitios de Unión , Humanos , Microscopía Electrónica , Simulación del Acoplamiento Molecular , Mutagénesis , Proteínas Proteolipídicas Asociadas a Mielina y Linfocito/metabolismo , Factor 88 de Diferenciación Mieloide/metabolismo , Unión Proteica , Proteínas Virales/genética , Proteínas Virales/metabolismoRESUMEN
A photochemically dissociating ligand in Ru(bpy)2(dmphen)Cl2 [bpy = 2,2'-bipyridine; dmphen = 2,9-dimethyl-1,10-phenanthroline] was found to be more cytotoxic on the ML-2 Acute Myeloid Leukemia cell line than Ru(bpy)2(H2O)22+ and prototypical cisplatin. Our findings illustrate the potential potency of diimine ligands in photoactivatable Ru(ii) complexes.