RESUMEN
Due to structural similarities and the possibility of connection between the two Aptian paleolakes in the Jatobá Basin and the Tucano Norte Sub-basin in North-eastern Brazil, the influence of the architecture of the crystalline basement under these lacustrine sedimentary rocks was analysed using gravimetric data near the faulted edges of the basins where the paleolakes are located. The Negra (Jatobá Basin) and Tonã (Tucano Norte Sub-basin) Hills are mainly sedimentary deposits of Aptian age and are linked to the post-rift I tectonic sequence. Aiming at the study of reservoirs analogous to pre-salt reservoirs, the gravimetric data were processed and interpreted to define the structural framework of the basin regions around these hills. Depth maps and density models were generated that could be analysed from various 3D perspectives, and the behaviour of the crystalline basement below these sedimentary sequences was investigated. In addition to the identification of horsts and semi-grabens that influenced the current relief pattern, the modelling showed that the Aptian paleolake sedimentary rocks of the Negra Hill are in the Ibimirim Low, which is approximately 2,900 m deep, while in the Tonã Hill, the sedimentary rocks are in the Salgado do Melão Low, which is approximately 5,100 m deep.
Asunto(s)
Lagos , BrasilRESUMEN
Natural variation separates Epstein-Barr virus (EBV) into type 1 and type 2 strains. Type 2 EBV is less transforming in vitro due to sequence differences in the EBV transcription factor EBNA2. This correlates with reduced activation of the EBV oncogene LMP1 and some cell genes. Transcriptional activation by type 1 EBNA2 can be suppressed through the binding of two PXLXP motifs in its transactivation domain (TAD) to the dimeric coiled-coil MYND domain (CC-MYND) of the BS69 repressor protein (ZMYND11). We identified a third conserved PXLXP motif in type 2 EBNA2. We found that type 2 EBNA2 peptides containing this motif bound BS69CC-MYND efficiently and that the type 2 EBNA2TAD bound an additional BS69CC-MYND molecule. Full-length type 2 EBNA2 also bound BS69 more efficiently in pull-down assays. Molecular weight analysis and low-resolution structures obtained using small-angle X-ray scattering showed that three BS69CC-MYND dimers bound two molecules of type 2 EBNA2TAD, in line with the dimeric state of full-length EBNA2 in vivo. Importantly, mutation of the third BS69 binding motif in type 2 EBNA2 improved B-cell growth maintenance and the transcriptional activation of the LMP1 and CXCR7 genes. Our data indicate that increased association with BS69 restricts the function of type 2 EBNA2 as a transcriptional activator and driver of B cell growth and may contribute to reduced B-cell transformation by type 2 EBV.
Asunto(s)
Proteínas Portadoras/metabolismo , Antígenos Nucleares del Virus de Epstein-Barr/genética , Antígenos Nucleares del Virus de Epstein-Barr/metabolismo , Herpesvirus Humano 4/genética , Proteínas Virales/genética , Proteínas Virales/metabolismo , Secuencia de Aminoácidos , Sustitución de Aminoácidos , Linfocitos B/metabolismo , Linfocitos B/virología , Sitios de Unión/genética , Proteínas Portadoras/química , Proteínas Portadoras/genética , Proteínas de Ciclo Celular , Línea Celular , Transformación Celular Viral/genética , Transformación Celular Viral/fisiología , Proteínas Co-Represoras , Proteínas de Unión al ADN , Antígenos Nucleares del Virus de Epstein-Barr/química , Genes Virales , Herpesvirus Humano 4/clasificación , Herpesvirus Humano 4/patogenicidad , Interacciones Microbiota-Huesped/genética , Interacciones Microbiota-Huesped/fisiología , Humanos , Modelos Moleculares , Mutación , Dominios y Motivos de Interacción de Proteínas , Estructura Cuaternaria de Proteína , Transactivadores/química , Transactivadores/genética , Transactivadores/metabolismo , Proteínas Virales/químicaRESUMEN
UNLABELLED: Sequence differences in the EBNA-2 protein mediate the superior ability of type 1 Epstein-Barr virus (EBV) to transform human B cells into lymphoblastoid cell lines compared to that of type 2 EBV. Here we show that changing a single amino acid (S442D) from serine in type 2 EBNA-2 to the aspartate found in type 1 EBNA-2 confers a type 1 growth phenotype in a lymphoblastoid cell line growth maintenance assay. This amino acid lies in the transactivation domain of EBNA-2, and the S442D change increases activity in a transactivation domain assay. The superior growth properties of type 1 EBNA-2 correlate with the greater induction of EBV LMP-1 and about 10 cell genes, including CXCR7. In chromatin immunoprecipitation assays, type 1 EBNA-2 is shown to associate more strongly with EBNA-2 binding sites near the LMP-1 and CXCR7 genes. Unbiased motif searching of the EBNA-2 binding regions of the differentially regulated cell genes identified an ETS-interferon regulatory factor composite element motif that closely corresponds to the sequences known to mediate EBNA-2 regulation of the LMP-1 promoter. It appears that the superior induction by type 1 EBNA-2 of the cell genes contributing to cell growth is due to their being regulated in a manner different from that for most EBNA-2-responsive genes and in a way similar to that for the LMP-1 gene. IMPORTANCE: The EBNA-2 transcription factor plays a key role in B cell transformation by EBV and defines the two EBV types. Here we identify a single amino acid (Ser in type 1 EBV, Asp in type 2 EBV) of EBNA-2 that determines the superior ability of type 1 EBNA-2 to induce a key group of cell genes and the EBV LMP-1 gene, which mediate the growth advantage of B cells infected with type 1 EBV. The EBNA-2 binding sites in these cell genes have a sequence motif similar to the sequence known to mediate regulation of the EBV LMP-1 promoter. Further detailed analysis of transactivation and promoter binding provides new insight into the physiological regulation of cell genes by EBNA-2.
Asunto(s)
Aminoácidos/metabolismo , Linfocitos B/metabolismo , Linfocitos B/virología , Antígenos Nucleares del Virus de Epstein-Barr/metabolismo , Proteínas Virales/metabolismo , Aminoácidos/genética , Ácido Aspártico/genética , Ácido Aspártico/metabolismo , Sitios de Unión/genética , Línea Celular , Inmunoprecipitación de Cromatina/métodos , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Antígenos Nucleares del Virus de Epstein-Barr/genética , Genes Virales/genética , Células HEK293 , Humanos , Regiones Promotoras Genéticas/genética , Receptores CXCR/genética , Receptores CXCR/metabolismo , Serina/genética , Serina/metabolismo , Activación Transcripcional/genética , Proteínas de la Matriz Viral/genética , Proteínas de la Matriz Viral/metabolismo , Proteínas Virales/genéticaRESUMEN
Autoinducer-2 (AI-2) a signal produced by a range of phylogenetically distant microorganisms, enables inter-species cell-cell communication and regulates many bacterial phenotypes. Certain bacteria can interfere with AI-2-regulated behaviours of neighbouring species by internalizing AI-2 using the Lsr transport system (encoded by the lsr operon). AI-2 imported by the Lsr is phosphorylated by the LsrK kinase and AI-2-phosphate is the inducer of the lsr operon. Here we show that in Escherichia coli the phosphoenolpyruvate phosphotransferase system (PTS) is required for Lsr activation and is essential for AI-2 internalization. Although the phosphorylation state of Enzyme I of PTS is important for this regulation, LsrK is necessary for the phosphorylation of AI-2, indicating that AI-2 is not phosphorylated by PTS. Our results suggest that AI-2 internalization is initiated by a PTS-dependent mechanism, which provides sufficient intracellular AI-2 to relieve repression of the lsr operon and, thus induce depletion of AI-2 from the extracellular environment. The fact that AI-2 internalization is not only controlled by the community-dependent accumulation of AI-2, but also depends on the phosphorylation state of PTS suggests that E. coli can integrate information on the availability of substrates with external communal information to control quorum sensing and its interference.