HIV relies on neddylation for ubiquitin ligase-mediated functions.
BACKGROUND
HIV and SIV defeat antiviral proteins by usurping Cullin-RING E3 ubiquitin ligases (CRLs) and likely influence other cellular processes through these as well. HIV-2 viral protein X (Vpx) engages the cullin4-containing CRL4 complex to deplete the antiviral protein SAMHD1. Vif expressed by HIV-1 and HIV-2 taps a cullin5 ubiquitin ligase complex to mark the antiviral protein APOBEC3G for destruction. Viral Protein R of HIV-1 (Vpr) assembles with the CRL4 ubiquitin ligase complex to deplete uracil-N-glycosylase2 (UNG2). Covalent attachment of the ubiquitin-like protein side-chain NEDD8 functionally activates cullins which are common to all of these processes.


RESULTS
The requirement for neddylation in HIV-1 and HIV-2 infectivity was tested in the presence of APOBEC3G and SAMHD1 respectively. Further the need for neddylation in HIV-1 Vpr-mediated depletion of UNG2 was probed. Treatment with MLN4924, an adenosine sulfamate analog which hinders the NEDD8 activating enzyme NAE1, blocked neddylation of cullin4A (CUL4A). The inhibitor hindered HIV-1 infection in the presence of APOBEC3G, even when Vif was expressed, and it stopped HIV-2 infection in the presence of SAMHD1 and Vpx. Consistent with these findings, MLN4924 prevented Vpx-mediated depletion of SAMHD1 in macrophages infected with Vpx-expressing HIV-2, as well as HIV-1 Vif-mediated destruction of APOBEC3G. It also stemmed Vpr-mediated UNG2 elimination from cells infected with HIV-1.


CONCLUSIONS
Neddylation plays an important role in HIV-1 and HIV-2 infection. This observation is consistent with the essential parts that cullin-based ubiquitin ligases play in overcoming cellular anti-viral defenses.
Michael D
MD
Nekorchuk
Hamayun J
HJ
Sharifi
Andrea K M
AK
Furuya
Robert
R
Jellinger
Center for Immunology and Microbial Disease, Albany Medical College, 43 New Scotland Avenue, Albany, NY 12208, USA. deNoroC@mail.amc.edu.
Carlos M C
CM
de Noronha
D000071480:APOBEC-3G Deaminase; D002460:Cell Line; D003564:Cytidine Deaminase / Q000378:metabolism; D015497:HIV-1 / Q000276:immunology / Q000502:physiology*; D015498:HIV-2 / Q000276:immunology / Q000502:physiology*; D006801:Humans; D020559:Monomeric GTP-Binding Proteins / Q000378:metabolism; D000075687:NEDD8 Protein; D000076106:SAM Domain and HD Domain-Containing Protein 1; D025801:Ubiquitin / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*; D054875:Ubiquitination; D014452:Ubiquitins / Q000378:metabolism*; D014779:Virus Replication
D000075687:NEDD8 Protein; C082860:NEDD8 protein, human; D025801:Ubiquitin; D014452:Ubiquitins; D044767:Ubiquitin-Protein Ligases; D000076106:SAM Domain and HD Domain-Containing Protein 1; C484280:SAMHD1 protein, human; D000071480:APOBEC-3G Deaminase; C464924:APOBEC3G protein, human; D003564:Cytidine Deaminase; D020559:Monomeric GTP-Binding Proteins