RESUMEN
Bacterial ABC toxin complexes (Tcs) comprise three core proteins: TcA, TcB and TcC. The TcA protein forms a pentameric assembly that attaches to the surface of target cells and penetrates the cell membrane. The TcB and TcC proteins assemble as a heterodimeric TcB-TcC subcomplex that makes a hollow shell. This TcB-TcC subcomplex self-cleaves and encapsulates within the shell a cytotoxic `cargo' encoded by the C-terminal region of the TcC protein. Here, we describe the structure of a previously uncharacterized TcC protein from Yersinia entomophaga, encoded by a gene at a distant genomic location from the genes encoding the rest of the toxin complex, in complex with the TcB protein. When encapsulated within the TcB-TcC shell, the C-terminal toxin adopts an unfolded and disordered state, with limited areas of local order stabilized by the chaperone-like inner surface of the shell. We also determined the structure of the toxin cargo alone and show that when not encapsulated within the shell, it adopts an ADP-ribosyltransferase fold most similar to the catalytic domain of the SpvB toxin from Salmonella typhimurium. Our structural analysis points to a likely mechanism whereby the toxin acts directly on actin, modifying it in a way that prevents normal polymerization.
Asunto(s)
Proteínas Bacterianas , Toxinas Bacterianas , Yersinia , Yersinia/genética , Toxinas Bacterianas/química , Toxinas Bacterianas/genética , Toxinas Bacterianas/metabolismo , Proteínas Bacterianas/genética , Proteínas Bacterianas/química , Proteínas Bacterianas/metabolismo , Transportadoras de Casetes de Unión a ATP/genética , Transportadoras de Casetes de Unión a ATP/química , Transportadoras de Casetes de Unión a ATP/metabolismo , Modelos Moleculares , Cristalografía por Rayos XRESUMEN
Oryctes rhinoceros nudivirus, a double-stranded DNA virus of the family Nudiviridae, is an important biocontrol agent of the coconut rhinoceros beetle (Coleoptera: Scarabaeidae). We present the genome sequences of six isolates of Oryctes rhinoceros nudivirus collected from the Philippines, Papua New Guinea, and Tanzania between the years 1977 and 2016.
RESUMEN
The development of the brain is sex-dimorphic, and as a result so are many neurological disorders. One approach for studying sex-dimorphic brain development is to measure gene expression in biological samples using RT-qPCR. However, the accuracy and consistency of this technique relies on the reference gene(s) selected. We analyzed the expression of ten reference genes in male and female samples over three stages of brain development, using popular algorithms NormFinder, GeNorm and Bestkeeper. The top ranked reference genes at each time point were further used to quantify gene expression of three sex-dimorphic genes (Wnt10b, Xist and CYP7B1). When comparing gene expression between the sexes expression at specific time points the best reference gene combinations are: Sdha/Pgk1 at E11.5, RpL38/Sdha E12.5, and Actb/RpL37 at E15.5. When studying expression across time, the ideal reference gene(s) differs with sex. For XY samples a combination of Actb/Sdha. In contrast, when studying gene expression across developmental stage with XX samples, Sdha/Gapdh were the top reference genes. Our results identify the best combination of two reference genes when studying male and female brain development, and emphasize the importance of selecting the correct reference genes for comparisons between developmental stages.
