Understanding olfaction at the molecular level is challenging due to the lack of crystallographic models of odorant receptors (ORs). To better understand the molecular mechanism of OR activation, we focused on chiral ()-muscone and other musk-smelling odorants due to their great importance and widespread use in perfumery and traditional medicine, as well as environmental concerns associated with bioaccumulation of musks with estrogenic/antiestrogenic properties. We experimentally and computationally examined the activation of human receptors OR5AN1 and OR1A1, recently identified as specifically responding to musk compounds. OR5AN1 responds at nanomolar concentrations to musk ketone and robustly to macrocyclic sulfoxides and fluorine-substituted macrocyclic ketones; OR1A1 responds only to nitromusks. Structural models of OR5AN1 and OR1A1 based on quantum mechanics/molecular mechanics (QM/MM) hybrid methods were validated through direct comparisons with activation profiles from site-directed mutagenesis experiments and analysis of binding energies for 35 musk-related odorants. The experimentally found chiral selectivity of OR5AN1 to ()- over ()-muscone was also computationally confirmed for muscone and fluorinated ()-muscone analogs. Structural models show that OR5AN1, highly responsive to nitromusks over macrocyclic musks, stabilizes odorants by hydrogen bonding to Tyr260 of transmembrane α-helix 6 and hydrophobic interactions with surrounding aromatic residues Phe105, Phe194, and Phe207. The binding of OR1A1 to nitromusks is stabilized by hydrogen bonding to Tyr258 along with hydrophobic interactions with surrounding aromatic residues Tyr251 and Phe206. Hydrophobic/nonpolar and hydrogen bonding interactions contribute, respectively, 77% and 13% to the odorant binding affinities, as shown by an atom-based quantitative structure-activity relationship model.

Protein tyrosine phosphatase 1B (PTP1B) is a known regulator of the insulin and leptin signaling pathways and is an active target for the design of inhibitors for the treatment of type II diabetes and obesity. Recently, cichoric acid (CHA) and chlorogenic acid (CGA) were predicted by docking methods to be allosteric inhibitors that bind distal to the active site. However, using a combination of steady-state inhibition kinetics, solution nuclear magnetic resonance experiments, and molecular dynamics simulations, we show that CHA is a competitive inhibitor that binds in the active site of PTP1B. CGA, while a noncompetitive inhibitor, binds in the second aryl phosphate binding site, rather than the predicted benzfuran binding pocket. The molecular dynamics simulations of the apo enzyme and cysteine–phosphoryl intermediate states with and without bound CGA suggest CGA binding inhibits PTP1B by altering hydrogen bonding patterns at the active site. This study provides a mechanistic understanding of the allosteric inhibition of PTP1B.

Recent rise in the number and therapeutic potential of genome engineering technologies has generated excitement in cardiovascular genetics. One significant barrier to their implementation is costly and time consuming reagent development for novel unique variants. Prior data have illuminated the potential for regional clustering of disease-causing genetic variants in known and potential novel functional protein domains. We hypothesized that most cardiovascular disease-relevant genes in ClinVar would display regional variant clustering, and that multiple variants within a regional hotspot could be targeted with limited prime editing reagents. We collated 2,471 high confidence pathogenic or likely pathogenic (P/LP) missense and truncating variants from 111 cardiovascular disease genes. We then defined a regional clustering index (RCI), the percent of P/LP variants in a given gene located within a pre-specified window around each variant. At a window size commensurate with maximally reported prime editing extension length, 78bp, we found that missense variants displayed a higher mean RCI than truncating variants. We next identified genes particularly attractive for pathogenic hotspot-targeted prime editing with at least 20 P/LP variants and observed that the mean RCI in missense variants remained higher than for truncating variants and for rare variants observed in the same genes in gnomAD (Mean±SD RCI 78bp : P/LP ClinVar Missense=5.2±5.9%; P/LP ClinVar Truncating=2.1±3.2%, gnomAD Missense=2±3.2%, gnomAD Truncating=1.1±2.4%. p<2.2e-16; ANOVA with post hoc Bonferroni correction). Further, we tested the feasibility of prime editing for multiple variants in a single hotspot in KCNH2, a gene with a high mean missense variant RCI. Sixty variants were induced in this hotspot in HEK293 cells with CRISPR-X. Correction of these variants was attempted with prime editing using two overlapping prime editing guide RNA extensions. The mean prime editing efficiency across CRISPR-X-enriched variants within this hotspot was 57±27%, including 3 P/LP variants. These data underscore the utility of pathogenic variant hotspots in the diagnosis and treatment of inherited cardiovascular disease.

The genetic architecture of inherited cardiomyopathies has mechanistic and potentially therapeutic relevance. We have shown that disease-associated variation in two cardiomyopathy-associated genes clusters in functional protein domains. Here, we extend this hypothesis to a comprehensive list of genes associated with cardiovascular disease. Using ClinVar, we identified 12,043 pathogenic or likely pathogenic (P/LP) variants across 190 cardiovascular disease-associated genes. Only P/LP variants with associated adjudication criteria were included. We interrogated these variants for regional clustering by ranking them by their number of P/LP neighbors within successively larger windows. We found that 87% of variants had at least one nearby variant within a 40 bp neighborhood, and 28% had ≥ 10 neighboring variants (Figure A, p<0.0001 vs. normal distribution). Within variant subtypes, 84% of missense variants and 70% of truncating variants neighbored at least 1 other missense or truncating variant, respectively. 21% of missense and 11% of truncating variants had ≥ 10 neighbors (p<0.0001). LDLR and FBN1 had the highest number of missense P/LP variants within a 40 bp neighborhood. We show that these neighborhoods overlap with functional domains of LDLR and FBN1 (Figure B, C). In summary, we demonstrate that a large portion of P/LP variants are regionally clustered in cardiovascular disease-associated genes, regardless of variant type, and align with known functional domains. Future directions will systematically apply these methods across the genome and explore the potential for novel domain identification and targeting these clusters with genome engineering.

Precision medicine has generated diagnoses for many patients with challenging undiagnosed disorders. Some individuals remain without a diagnosis despite comprehensive testing, and this impedes their treatment. This report addresses the role of personalized medicine in identifying effective therapy for an undiagnosed disease. A 22-year-old woman presented with chronic severe recurrent trismus, facial pain, progressive multicentric inflammatory and fibrotic masses, and high C-reactive protein. Sites of disease included the pterygomaxillary region, masseter muscles, mandible, lung, pericardium, intrabdominal cavity, and retroperitoneum. A diagnosis was not established after an extensive assessment, including multiple biopsies. The patient was subsequently evaluated under the Undiagnosed Diseases Program at the National Institutes of Health. Large scale genotyping, proteomic studies, and in vitro and gene expression analyses of fibroblasts obtained from a major disease locus were performed. Germline genetic testing did not identify strong candidate genes; proteomic studies of the patient's serum and bronchoalveolar lavage fluid and gene expression analyses of her cells were consistent with dysregulation of the tumor necrosis factor-alpha pathway. The patient's cultured fibroblasts were incubated with selected drugs, and cell proliferation was inhibited by hydroxychloroquine. Treatment of the patient with hydroxychloroquine conferred prolonged beneficial clinical effects, including stabilization of trismus and reduction of corticosteroid dose, C-reactive protein, and size of masses. This case represents an example