PEST sequences mediate heat shock factor 2 turnover by interacting with the Cul3 subunit of the Cul3-RING ubiquitin ligase

Abstract

Cullin-RING ubiquitin ligases promote the polyubiquitination and degradation of many important cellular proteins, which previous studies indicated can be targeted for degradation via interaction with BTB domaincontaining subunits of this E3 ligase complex. PEST domains are known to promote the degradation of proteins that contain them. However, the molecular mechanism by which PEST sequences promote degradation of these proteins is not understood. Here we show that the PEST sequences of a short-lived protein called HSF2 interact with Cullin3, a subunit of a Cullin-RING E3 ubiquitin ligase, and that this interaction mediates the Cul3-dependent ubiquitination and degradation of HSF2. These results indicate how, at the molecular level, PEST sequences can promote the proteolysis of proteins that contain them. They also expand understanding of the mechanisms by which substrates can be recruited to Cullin-RING E3 ubiquitin ligases to include interactions between PEST sequences and Cul3.

CRL4WDR1 Controls Polo-like Kinase Protein Abundance to Promote Bilobe Duplication, Basal Body Segregation and Flagellum Attachment in Trypanosoma brucei

“…While the D-box is a characteristic degradation signal for the APC/C ubiquitin ligase [40], the PEST motif in many proteins is recognized by a CRL-type ubiquitin ligase [10,11,41,42,43,44]. Our results demonstrated that CRL4 WDR1 recognizes the PEST motif in TbPLK, as the PEST deletion mutant (TbPLK-ΔPEST) was not able to bind to WDR1 (Fig 2C) and was stabilized (Fig 1B and 1C).…”

Differential Turnover of Myosin Chaperone UNC-45A Isoforms Increases in Metastatic Human Breast Cancer

“…PEST sequences also act as signals for protein rapid degradation through the ubiquitin-proteasome system. 40 Therefore, UNC-45A chaperone expression appeared to be regulated at transcription, alternative mRNA splicing, and differential turnover of its two major protein isoforms.…”

Dynamic transcription of ubiquitin genes under basal and stressful conditions and new insights into the multiple UBC transcript variants

“…Accumulation of ubiquitinated proteins may arise not only from a higher Ub conjugation rate, needed to remove damaged/unfolded proteins, but also from a reduced protein degradation: besides proteasome inhibitors, severe or sustained oxidative stress may impair proteasomal activity as well (Shang and Taylor, 2011). To ascertain if the Ub-dependent proteolytic machinery indeed functions properly under the stress environments investigated, the cellular content of HSF2 protein, a short-lived transcription factor whose steadystate level depends on the UPS activity, was also determined (Xing et al, 2010). As revealed by immunoblotting analysis, HSF2 accumulates only in cells treated with the proteasome inhibitor MG132, while in heat-shock and Arsenite-exposed cells, HSF2 levels are similar to or even lower than those detected in untreated control cells, which is consistent with a fully functional UPS (Fig.…”