RESUMEN
The structural protein (Gag) of the gypsy Drosophila retrovirus lacks matrix, but contains capsid and nucleocapsid domains. The Gag forms virus-like particles in a bacterial cell; besides, its capsid alone is able to form aggregates. However, aggregates assembled from the capsid were variable in size and displayed much less organization than particles formed by the whole Gag. The nucleocapsid exerts influence on the organization and structure of particles, and this function is directed by sequence of amino acid residues at its N-terminus (a nucleocapsid proximal part). The particle assembling occurs in the presence of any RNAs or single stranded DNA oligonucleotides.
Asunto(s)
Cápside/metabolismo , Productos del Gen gag/metabolismo , Multimerización de Proteína/fisiología , Retroviridae/metabolismo , Animales , Drosophila melanogaster , Escherichia coli/genética , Productos del Gen gag/genética , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Retroviridae/genéticaRESUMEN
The amino acid sequence of the drosophila retrovirus MDG4 (gypsy) structural protein Gag does not contain a canonical motif known for the majority of vertebrate retroviruses. Moreover, the protein translation can theoretically begin with two separated initiation codons located within its unique open reading frame. We designed constructs for expression of two theoretically possible variants of Gag polypeptide and investigated an ability of the each product to form virus-like particles in the bacterial cell, i.e. in the absence of eukaryotic cell factors. The results obtained showed that the both variants of the gypsy protein Gag form globular particles in the bacterial cell.
Asunto(s)
Drosophila melanogaster/virología , Productos del Gen gag/metabolismo , Virus de Insectos/metabolismo , Retroviridae/metabolismo , Factores de Transcripción/metabolismo , Virión/metabolismo , Secuencia de Aminoácidos , Animales , Escherichia coli/genética , Escherichia coli/metabolismo , Productos del Gen gag/química , Productos del Gen gag/genética , Datos de Secuencia Molecular , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Factores de Transcripción/química , Factores de Transcripción/genética , Virión/químicaRESUMEN
Current views of retrotransposons possessing long terminal repeats (LTRs) are described. The existing classification and element types isolated by genome organization are considered. Experimental data are summarized to demonstrate that the replicative cycle of a retrotransposon is not restricted to a single cell and that LTR retrotransposons are transferred between somatic cells with a rate comparable with the element transposition rate within the genome of one cell. The major mechanisms mediating the role of LTR retrotransposons in reorganization of the genome are considered with regard to the strategies of their horizontal and vertical transfer.
Asunto(s)
Transferencia de Gen Horizontal/genética , Genoma , Retroelementos/genética , Secuencias Repetidas Terminales/genética , Animales , HumanosRESUMEN
The view on Drosophila long terminal repeat (LTR) retrotransposons, which have three reading frames, as endogenous retroviruses or errantiviruses (ERVs, according to the latest ICTV nomenclature) is discussed. Data on the biology of ERVs and the mechanisms of their involvement in genetic instability of Drosophila are considered.
Asunto(s)
Drosophila/virología , Retrovirus Endógenos/genética , Virus de Insectos/genética , Animales , Drosophila/genética , Humanos , Sistemas de Lectura Abierta , Retroelementos/genética , Secuencias Repetidas Terminales , Terminología como AsuntoRESUMEN
Since retrovirus-like particles of gypsy (mdg4) are capable of interspecific transfer, other Drosophila melanogaster gypsy-related retrotransposons were tested for this property. As a donor and a recipient, D. melanogaster and D. virilis cultured cells were used. Recipient cell DNA was analyzed with probes directed to mdg1, mdg3, 17.6, 297, 412, or B104/roo. Transfer was demonstrated for mdg3, which lacks env. The possible mechanism of transfer is discussed.
Asunto(s)
Drosophila/genética , Transferencia de Gen Horizontal , Retroelementos , Animales , Células Cultivadas , Técnicas de Cocultivo , Drosophila/citología , Genes envAsunto(s)
Proteínas Serina-Treonina Quinasas/metabolismo , ARN/metabolismo , Proteínas Recombinantes/metabolismo , Factores de Transcripción/metabolismo , Animales , Quinasa de la Caseína II , Fosforilación , Proteínas Serina-Treonina Quinasas/genética , Proteínas Recombinantes/genética , RetroelementosAsunto(s)
Productos del Gen gag/metabolismo , Retroelementos/fisiología , Retroviridae/metabolismo , Membrana Celular/metabolismo , Escherichia coli/genética , Productos del Gen gag/biosíntesis , Productos del Gen gag/genética , Concentración de Iones de Hidrógeno , Iones/metabolismo , Sustancias Macromoleculares , Fosforilación , ARN/metabolismo , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Retroviridae/genética , Retroviridae/fisiología , Ensamble de Virus/fisiologíaAsunto(s)
Proteínas de Unión al ADN/metabolismo , Proteínas de Unión al ARN/metabolismo , Retroelementos , Secuencia de Aminoácidos , ADN/metabolismo , Proteínas de Unión al ADN/genética , Electroforesis en Gel de Poliacrilamida , Datos de Secuencia Molecular , Sistemas de Lectura Abierta , ARN/metabolismo , Proteínas de Unión al ARN/genéticaAsunto(s)
Escherichia coli/genética , Retroelementos , Factores de Transcripción/genética , Secuencia de Aminoácidos , Bacteriófago T7/genética , Secuencia de Bases , Clonación Molecular , ADN Recombinante , Electroforesis en Gel de Poliacrilamida , Datos de Secuencia Molecular , Sistemas de Lectura Abierta , Proteínas Recombinantes/genéticaRESUMEN
To investigate the gypsy functional activity, the possibility of conservation of its genetic information in VLP in the extracellular form has been examined. Preparations containing extracellular gypsy VLP from D. melanogaster and D. virilis were obtained. Non degradative full-sized polyA+ RNA and polyA+ RNA-DNA complexes of gypsy were revealed in the both preparations. The polypeptides with some specificity to gypsy nucleic acids were identified in VLP preparations. Some morphological and physical characteristics of the VLP preparations were obtained. The data obtained suggest the presence of non-degradative gypsy VLP in cultured media of D. melanogaster and D. virilis cells.
Asunto(s)
Elementos Transponibles de ADN , Animales , Células Cultivadas , Drosophila/genética , Drosophila melanogaster/genética , Genes Virales , Retroviridae/genéticaAsunto(s)
Proteínas de Unión al ADN/metabolismo , Drosophila melanogaster/genética , Virión/ultraestructura , Animales , Autorradiografía , Southern Blotting , Células Cultivadas , Medios de Cultivo , Elementos Transponibles de ADN , Drosophila melanogaster/metabolismo , Drosophila melanogaster/microbiología , Electroforesis en Gel de Poliacrilamida , Microscopía Electrónica , Virión/genética , Virión/metabolismoRESUMEN
Full-size hybrid RNA-DNA molecules of mdg1, mdg3 and copia have been discovered in cultured cells of Drosophila. The intracellular distribution of these molecules is considered. Hybrid molecules are found both in the nuclei and cytoplasm, the latter comprising the major portion of molecules. The membrane subcellular fraction enriched by poly(A) RNA and poly(A) RNA-DNA molecules of retretransposons is isolated from cytoplasm. The full-size linear double-stranded DNA of mdg1 is found in the same fraction. The data obtained make it possible to suppose that the process of reverse transcription on the mdg RNA is the way of regulation of mdg expression in the cell.
