A Small Molecule That Switches a Ubiquitin Ligase From a Processive to a Distributive Enzymatic Mechanism.

E3 ligases are genetically implicated in many human diseases, yet E3 enzyme mechanisms are not fully understood, and there is a strong need for pharmacological probes of E3s. We report the discovery that the HECT E3 Nedd4-1 is a processive enzyme and that disruption of its processivity by biochemical mutations or small molecules switches Nedd4-1 from a processive to a distributive mechanism of polyubiquitin chain synthesis. Furthermore, we discovered and structurally characterized the first covalent inhibitor of Nedd4-1, which switches Nedd4-1 from a processive to a distributive mechanism. To visualize the binding mode of the Nedd4-1 inhibitor, we used X-ray crystallography and solved the first structure of a Nedd4-1 family ligase bound to an inhibitor. Importantly, our study shows that processive Nedd4-1, but not the distributive Nedd4-1:inhibitor complex, is able to synthesize polyubiquitin chains on the substrate in the presence of the deubiquitinating enzyme USP8. Therefore, inhibition of E3 ligase processivity is a viable strategy to design E3 inhibitors. Our study provides fundamental insights into the HECT E3 mechanism and uncovers a novel class of HECT E3 inhibitors.

Identification of non-peptidic cysteine reactive fragments as inhibitors of cysteine protease rhodesain.

Rhodesain, the major cathepsin L-like cysteine protease in the protozoan Trypanosoma brucei rhodesiense, the causative agent of African sleeping sickness, is a well-validated drug target. In this work, we used a fragment-based approach to identify inhibitors of this cysteine protease, and identified inhibitors of T. brucei. To discover inhibitors active against rhodesain and T. brucei, we screened a library of covalent fragments against rhodesain and conducted preliminary SAR studies. We envision that in vitro enzymatic assays will further expand the use of the covalent tethering method, a simple fragment-based drug discovery technique to discover covalent drug leads.

Perceptions of Emergency Care by Sexual and Gender Minorities in Colorado: Barriers, Quality, and Factors Affecting Identity Disclosure.

INTRODUCTION: Expanding on data concerning emergency department (ED) use and avoidance by the sexual minority (those who identify as lesbian, gay, bisexual, queer, other [LGTBQ+]) and gender minority (those who identify as transgender, gender nonconforming, other) community may inform future ED LGTBQ+ training and clinical practice. Investigation objectives included characterizing rates of emergency care avoidance, identifying barriers to emergency care, and assessing emergency care quality and cultural competency for sexual and gender minorities. METHODS: In this population-based, cross-sectional needs assessment, sexual minority, gender minority, and/or cisgender heterosexual-identified participants were selected based on participants' subscription to newsletters or social media accounts for One Colorado, an LGBTQ+ advocacy organization. Each participant completed a single digital survey that collected qualitative and quantitative data about ED perception, use, and demographics. RESULTS: A total of 477 LGBTQ+ or heterosexual-identified individuals (mean age = 44.3 (standard deviation [SD] = 16.7)) participated in the study. Lifetime emergency care avoidance rates for gender minorities were markedly increased (odds ratio [OR] 3.8, 95% confidence interval [CI], 2.2 - 6.6; P <.001), while avoidance rates for sexual minorities were similar to those of cisgender heterosexual respondents (17% vs 14%; P <.001). Gender minorities were more likely than sexual minorities to both avoid emergency care due to fear of discrimination (43% vs 15%; P =.002) and to have experienced discrimination during their last ED visit (OR 11, [95% CI, 5-24]; P <.001). No significant differences were observed between participants in care avoidance due to financial reasons or prior negative experiences. No cited ED factors that influenced identity disclosure decisions were distinctly predictive. CONCLUSION: Gender minorities are more likely than sexual minorities and heterosexual cisgender individuals to report ED avoidance and discrimination at last ED visit. Future work characterizing deficits in LGBTQ+ ED care might reduce these avoidance and discrimination rates, enhancing the level of patient care provided to this population.

Fatal Rhabdomyolysis in a COVID-19 Patient on Rosuvastatin.

It is well-established by now that COVID-19 can have a wide variety of neuromuscular manifestations, including rhabdomyolysis. Weakness and elevated creatinine kinase (CK) have been documented as the initial presentation of COVID-19. Myopathy from statin use has also been well-established since the introduction of this class of medication, and the common pathologic mechanism of both entities may have been mitochondrial dysfunction. We present here the case of a COVID-19 patient on rosuvastatin who developed rhabdomyolysis with CK above 1,000,000 units/L. The patient did not present with any respiratory difficulty and responded poorly to treatment, resulting in his untimely demise. COVID-19 may have accentuated an otherwise survivable condition by means of extra stress on mitochondrial homeostasis. Understanding the actual mechanism will be important in the development and utilization of medications in the fight against COVID-19.