The HIV1 Protein Vpr Acts to Enhance Constitutive DCAF1-Dependent UNG2 Turnover.

PLoS One. 2012; 7(1): e30939
Wen X, Casey Klockow L, Nekorchuk M, Sharifi HJ, de Noronha CM

The HIV1 protein Vpr assembles with as well as acts by an ubiquitin ligase formidable that includes DDB1 as well as cullin 4 (CRL4) to cause G2 dungeon cycle arrest as well as to foster degradation of both uracil DNA glycosylase 2 (UNG2) as well as single-strand resourceful mono-functional uracil DNA glycosylase 1 (SMUG1). DCAF1, an adaptor protein, is compulsory for Vpr-mediated G2 arrest by a ubiquitin ligase complex. In work described here, we used UNG2 as a model substrate to study how Vpr acts by a ubiquitin ligase complex. We examined whether DCAF1 is essential for Vpr-mediated degradation of UNG2 as well as SMUG1. We further investigated whether Vpr is compulsory for recruiting substrates to a ubiquitin ligase or acts to raise its duty as well as whether this parallels Vpr-mediated G2 arrest.We found that DCAF1 plays an important role in Vpr-independent UNG2 as well as SMUG1 depletion. UNG2 assembled with a ubiquitin ligase formidable in a absence of Vpr, but Vpr enhanced this interaction. Further, Vpr-mediated encouragement of UNG2 degradation correlated with low Vpr countenance levels. Vpr concentrations exceeding a threshold blocked UNG2 lassitude as well as enhanced its accumulation in a dungeon nucleus. A similar dose-dependent trend was seen for Vpr-mediated dungeon cycle arrest.This work identifies UNG2 as well as SMUG1 as novel targets for CRL4(DCAF1)-mediated degradation. It further shows that Vpr enhances rsther than than enables a interaction between UNG2 as well as a ubiquitin ligase. Vpr augments CRL4(DCAF1)-mediated UNG2 degradation at low concentrations but antagonizes it at high concentrations, allowing nuclear accumulation of UNG2. Further, a protein that is targeted to cause G2 arrest behaves much like UNG2. Our findings provide a basement for determining whether a CRL4(DCAF1) formidable is alone responsible for dungeon cycle-dependent UNG2 turnover as well as will additionally aid in establishing conditions necessary for a identification of additional targets of Vpr-enhanced degradation.

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