The precellular scenario of genovirions.

A new hypothesis of the ancestors of contemporary viruses, the genovirions is proposed. This concept emphasizes the close connection between the evolution of viruses and the proto-cells. Recent and mounting evidences from comparative genomics indicate that both RNA and DNA viruses evolved from primordial genetic elements before proto-cells existed.

Molecular characterization of proteolytic processing of the Gag proteins of human spumaretrovirus.

Molecular characterization of proteolytic processing of the human spumaretrovirus (HSRV) Gag proteins and the precise determination of cleavage sites was performed. For in vitro processing of recombinant HSRV Gag proteins, a recombinant enzymatically active HSRV protease was employed. Recombinant Gag proteins and protease were cloned and expressed as hexa-histidine-tagged proteins in pET-32b and pET-22b vectors, respectively, in the E.

Coactivators p300 and PCAF physically and functionally interact with the foamy viral trans-activator.

Background: Foamy virus Bel1/Tas trans-activators act as key regulators of gene expression and directly bind to Bel1 response elements (BRE) in both the internal and the 5'LTR promoters leading to strong transcriptional trans-activation. Cellular coactivators interacting with Bel1/Tas are unknown to date.

Results: Transient expression assays, co-immunoprecipitation experiments, pull-down assays, and Western blot analysis were used to demonstrate that the coactivator p300 and histone acetyltransferase PCAF specifically interact with the retroviral trans-activator Bel1/Tas in vivo.

Comparative functional characterization of the feline foamy virus transactivator reveals its species specificity.

Foamy virus (FV) Bel1/Tas transactivators act as key regulators of gene expression and directly bind DNA Bel1 response elements (BREs) in both the internal (IP) and 5'LTR promoters. Here, we report the mapping and the virus species specificity of the nonhomologous feline foamy virus (FFV) BREs in both promoters. The data indicate that FFV Bel1 did not bind the primate FV IP.

Proteolytic processing of foamy virus Gag and Pol proteins.

The foamy viral proteases (FV PRs) are set apart from other retroviral processing enzymes by unique features. The first remarkable property is that FV PRs are enzymatically active as high-molecular-mass Pro-Pol proteins. Hence there exist multiple forms of active FV PRs that likely contribute to cleavage site specificity.