SUMMARY The eukaryotic chaperonin TRiC/CCT uses ATP cycling to fold many essential proteins that other chaperones cannot fold. This 1 MDa hetero-oligomer consists of two identical stacked rings assembled from eight paralogous subunits, each containing a conserved ATP-binding domain. Here, we report a dramatic asymmetry in the ATP utilization cycle of this ring-shaped chaperonin, despite its apparently symmetric architecture. Only four of the eight different subunits bind ATP at physiological concentrations. ATP binding and hydrolysis by the low-affinity subunits is fully dispensable for TRiC function in vivo. The conserved nucleotide-binding hierarchy among TRiC subunits is evolutionarily modulated through differential nucleoside contacts. Strikingly, high-and low-affinity subunits are spatially segregated within two contiguous hemispheres in the ring, generating an asymmetric power stroke that drives the folding cycle. This unusual mode of ATP utilization likely serves to orchestrate a directional mechanism underlying TRiC/CCT’s unique ability to fold complex eukaryotic proteins.

During terminal differentiation, the global protein complement is remodeled, as epitomized by erythrocytes, whose cytosol is ~98% globin. The erythroid proteome undergoes a rapid transition at the reticulocyte stage; however, the mechanisms driving programmed elimination of preexisting cytosolic proteins are unclear. We found that a mutation in the murine Ube2o gene, which encodes a ubiquitin-conjugating enzyme induced during erythropoiesis, results in anemia. Proteomic analysis suggested that UBE2O is a broad-spectrum ubiquitinating enzyme that remodels the erythroid proteome. In particular, ribosome elimination, a hallmark of reticulocyte differentiation, was defective in Ube2o−/− mutants. UBE2O recognized ribosomal proteins and other substrates directly, targeting them to proteasomes for degradation. Thus, in reticulocytes, the induction of ubiquitinating factors may drive the transition from a complex to a simple proteome.

IMPORTANCETransoral robotic surgery has been widely adopted since approval by the US Food and Drug Administration in December 2009, despite limited comparative data.OBJECTIVE To compare the long-term outcomes of transoral robotic surgery with those of nonrobotic surgery for patients with early-stage oropharyngeal cancer. DESIGN, SETTING, AND PARTICIPANTSA retrospective cohort comparative effectiveness analysis was performed of patients in the National Cancer Database with clinical T1 and T2 oropharyngeal squamous cell carcinoma diagnosed between January 1, 2010, and December 31, 2015, who underwent definitive robotic and nonrobotic surgery. Multivariable Cox proportional hazards regression analysis and propensity score matching were performed in patients with known human papillomavirus status to adjust for patient-and disease-related covariates. Survival after robotic and nonrobotic surgery was also compared in 3 unrelated cancers: prostate, endometrial, and cervical cancer. Statistical analysis was performed from April 10, 2019, to May 21, 2020. MAIN OUTCOMES AND MEASURES Overall survival.RESULTS Of 9745 patients (7652 men [78.5%]; mean [SD] age, 58.8 [9.6] years) who met inclusion criteria, 2694 (27.6%) underwent transoral robotic surgery. There was a significant increase in the use of robotic surgery from 18.3% (240 of 1309) to 35.5% (654 of 1841) of all surgical procedures for T1 and T2 oropharyngeal cancers from 2010 to 2015 (P = .003). Robotic surgery was associated with lower rates of positive surgical margins (12.5% [218 of 1746] vs 20.3% [471 of 2325]; P < .001) and lower use of adjuvant chemoradiotherapy (28.6% [500 of 1746] vs 35.7% [831 of 2325]; P < .001). Among 4071 patients with known human papillomavirus status, robotic surgery was associated with improved overall survival compared with nonrobotic surgery in multivariable Cox proportional hazards regression (hazard ratio [HR], 0.74; 95 CI, 0.61-0.90; P = .002). Similar results were seen when analyzing only the subset of facilities offering both robotic and nonrobotic surgery. The 5-year overall survival was 84.8% vs 80.3% among patients undergoing robotic vs nonrobotic surgery in propensity score-matched cohorts (P = .001). By contrast, there was no evidence that robotic surgery was associated with improved survival in other cancers, such as prostate cancer (HR, 0.92; 95% CI, 0.79-1.07; P = .26), endometrial cancer (HR, 0.97; 95% CI, 0.90-1.04; P = .36), and cervical cancer (HR, 1.27; 95% CI, 0.96-1.69; P = .10). CONCLUSIONS AND RELEVANCEThis study suggests that transoral robotic surgery was associated with improved surgical outcomes and survival compared with nonrobotic surgery in patients with early-stage oropharyngeal cancer. Evaluation in comparative randomized trials is warranted.

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