Anti-Ubiquitin polyclonal antibody

HBZ is expressed by the complex retrovirus, Human T-cell Leukemia Virus type 1, and implicated in pathological effects associated with viral infection. From the nucleus, HBZ alters gene expression by interacting with a variety of transcriptional regulatory proteins, among which is c-Jun. Previously, one of the three HBZ variants, HBZ(US), was reported to decrease c-Jun expression by promoting its degradation. Here we show that another variant, HBZ(S1), produces the opposite effect. In the presence of HBZ(S1), c-Jun expression increases due to its stabilization. Our data suggest that this effect requires the ability of HBZ(S1) to interact with c-Jun. We provide evidence that HBZ(S1) inhibits the proteosomal degradation of c-Jun initiated by the Cop1-containing ubiquitin ligase complex. HBZ(S1) is the most abundant variant in HTLV-1-infected T-cells, and our data indicate that levels of c-Jun expression in infected cells are consistent with effects of HBZ(S1).

Proline is one of the abundant amino acids in grape must, but in winemaking processes it is poorly assimilated by the yeast Saccharomyces cerevisiae. This often causes a nitrogen deficiency during fermentation and proline accumulation in wine. Our previous study showed that arginine inhibits proline utilization by specifically inducing the endocytosis of the high-affinity proline transporter Put4. However, the detailed mechanisms underlying this induction are still unclear. Here, we propose a possible mechanism mediated by the ubiquitin ligase Rsp5 and its adaptor protein, Art3. First, we found that the ubiquitination activity of Rsp5 was essential for the arginine-induced endocytosis of Put4. Because Put4 contains no Rsp5-binding motif, we next screened an adaptor protein that plays a role in the arginine-induced endocytosis of Put4. Our genetic and biochemical analyses clearly revealed that the ART3 gene-disrupted cells were defective in Put4 endocytosis, indicating that Art3 is a key regulator for Put4 endocytosis. More importantly, we discovered that deletion of ART3 remarkably canceled the inhibitory effects of arginine on proline utilization. The present results could hold promise for the development of wine yeast strains that can efficiently assimilate the abundant proline in grape must during the fermentation processes. (c) 2020 Elsevier Inc. All rights reserved.