Crt10 directs the cullin-E3 ligase Rtt101 to nonfunctional 25S rRNA decay

Abstract

Nonfunctional mutant ribosomal RNAs in 40S or 60S subunits are selectively degraded in eukaryotic cells (nonfunctional rRNA decay, NRD). We previously reported that NRD of 25S rRNA required cullin-E3 ligase Rtt101 and its associating factor Mms1, both of which are involved in DNA repair. Although Mms22, an accessory component of the E3 complex, was suggested to direct the E3 complex to DNA repair, the factor that directs the complex to 25S NRD currently remains unknown. We herein demonstrated that another accessory component, Crt10 was required for 25S NRD, but not for DNA repair, suggesting that this accessory component specifies the function of the E3 complex differently. We also identified two distinct Crt10-containing E3 complexes, one of which contained the Paf1 complex, a Pol-II binding complex that modulates the transcription of stress-related genes. Our results showed the convergence of multiple pathways for stresses that harm nucleic acids and provided a molecular framework for the substrate diversity of the E3 complex.

Oxidation and alkylation stresses activate ribosome-quality control

“…4a, b). Here, we analyzed the level of ribosomal ubiquitylation after treatment with MMS in the presence and absence of either Hel2, Mms21, or Rtt101, the latter two of which are known to function during non-functional ribosome decay 52,53 . A complete loss of ribosomal ubiquitylation was only observed in hel2Δ cells (Fig.…”

Ubiquitin-mediated mechanisms of translational control

“…2B) [43]. With regard to 25S NRD, the E3 ubiquitin ligase complex Rtt101-Mms1-Crt10 and the ubiquitin-binding complex Cdc48 have been involved in subunit dissociation [44][45][46]. The subsequent recognition and proteolysis of the 60S subunit by proteasome favors the exposure of the 25S rRNA to ribonucleases (Fig.…”

Sequential Ubiquitination of Ribosomal Protein uS3 Triggers the Degradation of Non-functional 18S rRNA

“…In NRD, subunit dissociation of the non-functional 80S ribosome is a prerequisite step for degradation of the non-functional subunit. 25S NRD requires an E3 ubiquitin ligase complex, and proteins associated with a non-functional ribosome are ubiquitinated in an Rtt101-Mms1-dependent manner (Fujii et al, 2009), with Crt10 responsible for substrate recognition of the Rtt101-Mms1-containing E3 ligase complex (Sakata et al, 2015). The non-functional and ubiquitinated 60S subunit is dissociated from the 40S subunit in a Cdc48-Npl4-Ufd1 complex (Cdc48 complex)-dependent manner before it is attacked by the proteasome (Fujii et al, 2012).…”