The incorporation of nonacetate starter units during type II polyketide biosynthesis helps diversify natural products. Currently, there are few enzymatic strategies for the incorporation of nonacetate starter units in type II polyketide synthase (PKS) pathways. Here we report the crystal structure of AuaEII, the anthranilate:CoA ligase responsible for the generation of anthraniloyl-CoA, which is used as a starter unit by a type II PKS in aurachin biosynthesis. We present structural and protein sequence comparisons to other aryl:CoA ligases. We also compare the AuaEII crystal structure to a model of a CoA ligase homologue, AuaE, which is present in the same gene cluster. AuaE is predicted to have the same fold as AuaEII, but instead of CoA ligation, AuaE catalyzes acyl transfer of anthranilate from anthraniloyl-CoA to the acyl carrier protein (ACP). Together, this work provides insight into the molecular basis for starter unit selection of anthranilate in type II PKS biosynthesis.

Despite broad appreciation of their clinical utility, it has been unclear how vitamin B12 and folic acid (FA) function at the molecular level to directly prevent their hallmark symptoms of deficiency like anemia or birth defects. To this point, B12 and FA have largely been studied as cofactors for enzymes in the one-carbon (1C) cycle in facilitating the de novo generation of nucleotides and methylation of DNA and protein. Here, we report that B12 and FA function as natural antagonists of aryl hydrocarbon receptor (AhR). Our studies indicate that B12 and FA bind AhR directly as competitive antagonists, blocking AhR nuclear localization, XRE binding, and target gene induction mediated by AhR agonists like 2,3,7,8-tetrachlorodibenzodioxin (TCDD) and 6-formylindolo[3,2-b]carbazole (FICZ). In mice, TCDD treatment replicated many of the hallmark symptoms of B12/FA deficiency and cotreatment with aryl hydrocarbon portions of B12/FA rescued mice from these toxic effects. Moreover, we found that B12/FA deficiency in mice induces AhR transcriptional activity and accumulation of erythroid progenitors and that it may do so in an AhR-dependent fashion. Consistent with these results, we observed that human cancer samples with deficient B12/FA uptake demonstrated higher transcription of AhR target genes and lower transcription of pathways implicated in birth defects. In contrast, there was no significant difference observed between samples with mutated and intact 1C cycle proteins. Thus, we propose a model in which B12 and FA blunt the effect of natural AhR agonists at baseline to prevent the symptoms that arise with AhR overactivation.

Introduction: Intrahepatic Cholestasis of Pregnancy (ICP) is a common maternal liver disease; development can result in devastating consequences, including sudden fetal death and stillbirth. Currently, recognition of ICP only occurs following onset of clinical symptoms. Objective: Investigate the maternal hair metabolome for predictive biomarkers of ICP. Methods: The maternal hair metabolome (gestational age of sampling between 17+4 weeks and 41 weeks) of 38 Chinese women with ICP and 46 pregnant controls was analysed using gas chromatography-mass spectrometry. Results: Of 105 metabolites detected in hair, none were significantly associated with ICP. Conclusion: ICP development was not detectable in full-length hair strands, suggesting that ICP has rapid development -only distinguishable later in pregnancy.

Health Care Leaders (HCLs) faced unprecedented challenges during the initial phases of the COVID-19 pandemic. Leaders played an important role in shaping the experiences of Health Care Workers (HCWs) during this time. However, research is needed on how HCWs experienced and characterized HCLs’ response and support. The aim of our study was to examine HCWs’ experiences with leadership and to identify aspects of HCLs’ response that were effective in supporting HCWs in their roles during the early phases of the pandemic. This was a qualitative study based on open-ended semi-structured interviews conducted (June 1- July 18, 2020) with frontline HCWs during the first wave of the COVID-19 pandemic in Connecticut, USA. Participants (N = 45) included physicians, nurses, respiratory therapists and patient care assistants who worked in inpatient and outpatient settings in various specialties, roles and 3 health systems across Connecticut, USA during the COVID-19 pandemic. Participants were offered a $25 gift card as an incentive for participation. We used inductive techniques derived from grounded theory to develop themes. We identified 6 main themes related to leadership response and support of HCWs during the pandemic namely: 1) Effective communication and transparency; 2) Prioritizing their health and safety; 3) Employee scheduling considerations: autonomy, assignment support and respite; 4) Appreciation- financial and nonfinancial; 5) Showing up and listening and 6) Stepping up with resources. Our findings can inform leadership responses to future pandemics and other unanticipated crises leading to strengthening of the health care system as a whole.