Abstract
ABSTRACTThere has been extraordinary progress in understanding the roles of lentiviral accessory proteins in antagonizing host antiviral defense proteins. However, the precise primary function of the accessory gene Vpr remains elusive. Here we suggest that engagement with the DNA damage response is an important function of primate lentiviral Vpr proteins because of its conserved function among diverse lentiviral lineages. In contrast, we show that, for HIV-1, HIV-2, and related Vpr isolates and orthologs, there is a lack of correlation between DNA damage response activation and interaction with the host SLX4 protein complex of structure specific endonucleases; some Vpr proteins are able to interact with SLX4, but the majority are not. Using the clustered regularly interspaced short palindromic repeat (CRISPR)/Cas9 method to knock out SLX4, we formally showed that HIV-1 and HIV-2 Vpr orthologs can still activate the DNA damage response and cell cycle arrest in the absence of SLX4. Together, our data suggest that activation of the DNA damage response, but not SLX4 interaction, is conserved and therefore indicative of an important function of Vpr. Our data also indicate that Vpr activates the DNA damage response through an SLX4-independent mechanism that remains uncharacterized.
Highlights
HIV-1 and other primate lentiviruses encode accessory proteins that enhance viral infectivity [1]
Since HIV-1 and HIV-2 both replicate in their human host and yet have very different primate origins, we reasoned that assaying the ability of Vpr proteins from both viruses to activate the DNA damage response and/or to interact with SLX4 would help shed light on the importance of these functions for primate lentiviruses
It has been previously shown that HIV-2, like HIV-1, causes G2 arrest in human cells [29, 30], a result that we were able to reproduce with our associated virus (AAV) expression system with no appreciable background activation
Summary
HIV-1 and other primate lentiviruses encode accessory proteins that enhance viral infectivity [1]. One major caveat with respect to experiments using proteins from diverse primate lentiviruses to assay functions in human cells is that, due to the evolutionary arms race between the virus and its host, they may have evolved to be species-specific interactions [22]. This can be circumvented by studying HIV-1 and HIV-2, which both naturally infect humans and yet have distinct evolutionary histories. HIV-1 and HIV-2 present a powerful toolset to look more in depth at conservation of function between divergent lentiviruses, as they have both evolved to infect humans but have distinct parental viruses and evolutionary histories
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