Abstract
There has been accumulating evidence for the involvement of retroviral integrase (IN) in the reverse transcription of viral RNA. We previously identified a host factor, survival motor neuron-interacting protein 1 (SIP1/Gemin2) that binds to human immunodeficiency virus type 1 (HIV-1) IN and supports HIV-1 infection apparently at reverse transcription step. Here, we demonstrated that HIV-1 IN together with SIP1 augments reverse transcriptase (RT) activity by enhancing the assembly of RT on viral RNA in vitro. Synthetic peptides corresponding to the binding motifs within IN that inhibited the IN-SIP1 interaction abrogated reverse transcription in vitro and in vivo. Furthermore, knockdown of SIP1 reduced intracellular stability and multimer formation of IN through proteasome-mediated degradation machinery. Taken together, SIP1 appears to stabilize functional multimer forms of IN, thereby promoting the assembly of IN and RT on viral RNA to allow efficient reverse transcription, which is a prerequisite for efficient HIV-1 infection.
Highlights
Upon infection of host cells with a retrovirus, the viral genome is subjected to several processes that include uncoating, reverse transcription of the viral genomic RNA into a cDNA copy by reverse transcriptase (RT), transport of this cDNA into the nucleus, and integration of the cDNA into the host chromosome
We showed that SIP1 stabilizes the formation of a functional multimer of IN, thereby promoting the assembly of IN and RT on viral RNA to allow an efficient reverse transcription
All of the IN mutations that cause reverse transcription defective phenotype, at least tested here, significantly reduced the intracellular interaction with SIP1, suggesting that the interaction of IN with SIP1 is critical for efficient reverse transcription in the human immunodeficiency virus type 1 (HIV-1) infection cycle
Summary
Upon infection of host cells with a retrovirus, the viral genome is subjected to several processes that include uncoating, reverse transcription of the viral genomic RNA into a cDNA copy by reverse transcriptase (RT), transport of this cDNA into the nucleus, and integration of the cDNA into the host chromosome. These early events are mediated through the interactions of several viral proteins and host factors with the viral genome, often referred as reverse transcription complex (RTC) or preintegration complex (PIC) [1,2].
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