Impairment of human immunodeficiency virus type-1 integrase SUMOylation correlates with an early replication defect.

HIV-1 integrase (IN) orchestrates the integration of the reverse transcribed viral cDNA into the host cell genome and participates also in other steps of HIV-1 replication. Cellular and viral factors assist IN in performing its multiple functions, and post-translational modifications contribute to modulate its activities. Here, we show that HIV-1 IN is modified by SUMO proteins and that phylogenetically conserved SUMOylation consensus motifs represent major SUMO acceptor sites.

A nuclear export signal within the structural Gag protein is required for prototype foamy virus replication.

Background: The Gag polyproteins play distinct roles during the replication cycle of retroviruses, hijacking many cellular machineries to fulfill them. In the case of the prototype foamy virus (PFV), Gag structural proteins undergo transient nuclear trafficking after their synthesis, returning back to the cytoplasm for capsid assembly and virus egress. The functional role of this nuclear stage as well as the molecular mechanism(s) responsible for Gag nuclear export are not understood.

[SUMO in the viral world].

Post-translational modifications, such as SUMOylation, are exam- ples of cellular machineries hijacked by viruses to efficiently replicate. SUMOylation, which consists in the conjugation of small ubiquitin-like modi- fier (SUMO) peptides to a substrate, is exploited or hampered by numerous viruses during infection. Several viral proteins are SUMOylated, causing modulation of sub-cellular localization, stability or modifications of protein activities.

[Nuclear export of retroviral messenger RNA].

Many cellular and viral proteins and nucleic acids shuttle between the nucleus and the cytoplasm. It is increasingly clear that nuclear import and export involve complex and finely regulated mechanisms. Nuclear export is absolutely necessary for viral protein synthesis and particle assembly for retroviruses showing a nuclear step during their replication cycle.