2.1 Å crystal structure of the Mycobacterium tuberculosis serine hydrolase, Hip1, in its anhydro-form (Anhydrohip1).

The 2.6 Å crystal structure of the apo form of Hip1 (hydrolase important for pathogenesis) has been previously reported. However, very little is known about the active site architecture of this M. tuberculosis (Mtb), serine hydrolase drug target. To begin mapping the active site of Hip1, we cocrystallized Hip1 with the irreversible serine protease inhibitor, 4-(2-aminoethyl)-benzenesulfonylfluoride (AEBSF). We chose AEBSF for cocrystallization with Hip1 since the similar inhibitor, phenylmethylsulfonyl fluoride (PMSF), interestingly exhibited no activity against Hip1. We obtained crystals that diffracted to 2.1 Å but to our bewilderment, we did not observe any electron density for the inhibitor in the omit map for the Hip1-AEBSF complex. Rather, in the active site, dehydroalanine (dAla) was found to occupy the expected position of the catalytic Ser228, thus yielding anhydrohip1. Here we present a comparative analysis of the crystal structures of anhydrohip1 and Hip1 and provide a mechanism for the conversion of the enzyme to the anhydro-form through reaction with AEBSF. With the aid of molecular docking, we propose an explanation for the differential inhibition of Hip1 by AEBSF and PMSF. We also present a preliminary definition of the S1 and S2 pockets of the protease's active site and propose a mechanism for a ligand-induced conformational change within the S2 pocket. Finally, we expand upon the previous demarcation of the putative lipid binding pocket in the α-domain of the enzyme. We believe that this detailed analysis of the structures of anhydrohip1 and Hip1 provides valuable information useful for the structure-based drug design of novel Hip1-directed Mtb therapeutics.

Circulating endocannabinoids and genetic polymorphisms as predictors of posttraumatic stress disorder symptom severity: heterogeneity in a community-based cohort.

The endocannabinoid signaling system (ECSS) regulates fear and anxiety. While ECSS hypoactivity can contribute to symptoms of established post-traumatic stress disorder (PTSD), the role of the ECSS in PTSD development following trauma is unknown. A prospective, longitudinal cohort study of 170 individuals (47% non-Hispanic Caucasian and 70% male) treated at a level 1 trauma center for traumatic injury was carried out. PTSD symptom assessments and blood were obtained during hospitalization and at follow-up (6-8 months post injury). Serum concentrations of the endocannabinoids N-arachidonoylethanolamine (AEA) and 2-arachidonoylglycerol (2-AG) were determined at both time points and selected genetic polymorphisms in endocannabinoid genes, including rs324420 in fatty acid amide hydrolase, were assessed. For the entire sample, serum concentrations of AEA at hospitalization were significantly higher in those diagnosed with PTSD at follow-up (p = 0.030). Serum concentrations of 2-AG were significantly, positively correlated with PTSD symptom severity at follow-up only in minorities (p = 0.014). Minority participants (mostly Black/African American) also demonstrated significant, negative correlations between serum AEA concentrations and PTSD symptom severity both measured at hospitalization (p = 0.015). The A/A genotype at rs324420 was associated with significantly higher PTSD symptom severity (p = 0.025) and occurred exclusively in the Black participants. Collectively, these results are contrary to our hypothesis and find positive associations between circulating endocannabinoids and risk for PTSD. Minority status is an important modulator of the association between endocannabinoids and risk for PTSD, suggesting that the ECSS contributes to risk most significantly in these individuals and the contextual factors related to these findings should be further explored.

Inhibition of Mycobacterium tuberculosis Dethiobiotin Synthase (MtDTBS): Toward Next-Generation Antituberculosis Agents.

Mycobacterium tuberculosis dethiobiotin synthase (MtDTBS) is a crucial enzyme involved in the biosynthesis of biotin in the causative agent of tuberculosis, M. tuberculosis. Here, we report a binder of MtDTBS, cyclopentylacetic acid 2 (KD = 3.4 ± 0.4 mM), identified via in silico screening. X-ray crystallography showed that 2 binds in the 7,8-diaminopelargonic acid (DAPA) pocket of MtDTBS. Appending an acidic group to the para-position of the aromatic ring of the scaffold revealed compounds 4c and 4d as more potent binders, with KD = 19 ± 5 and 17 ± 1 µM, respectively. Further optimization identified tetrazole 7a as a particularly potent binder (KD = 57 ± 5 nM) and inhibitor (Ki = 5 ± 1 µM) of MtDTBS. Our findings highlight the first reported inhibitors of MtDTBS and serve as a platform for the further development of potent inhibitors and novel therapeutics for the treatment of tuberculosis.

A Randomized Trial of Modified Prolonged Exposure to Prevent the Development of Posttraumatic Stress Disorder in Patients Hospitalized With Traumatic Injuries.

Individuals who require hospitalization after traumatic injuries are at increased risk for developing posttraumatic stress disorder (PTSD); however, few early behavioral interventions have been effective at preventing PTSD within this population. The aim of this pilot study was to assess the feasibility and effectiveness of modified prolonged exposure therapy (mPE) to prevent PTSD and depression symptoms among patients hospitalized after a DSM-5 single-incident trauma. Hospitalized patients were eligible if they screened positive for PTSD risk. Participants (N = 74) were randomly assigned in a parallel-groups design to receive mPE (n = 38) or standard of care treatment (SoC; n = 36) while admitted to the hospital after a traumatic injury. Individuals randomized to the intervention condition received one (42.1%), two (36.8%), or three sessions (15.8%) of mPE, mainly depending on length of stay. There were no significant differences between groups regarding PTSD or depression severity at 1- or 3-months posttrauma, except for more PTSD diagnoses in the intervention group after 1 month, ϕ = -.326. Intervention differences were nonsignificant when we took baseline PTSD symptoms and the nonindependence of the repeated measurements within the data into account. No adverse events were reported. Overall, mPE was no more effective than SoC for hospitalized, traumatic injury survivors with a high PTSD risk. The results may point to a need for a stepped-care approach, where intervention protocols focus on first briefly treating individuals who are actively exhibiting acute stress reactions, then extensively treating those whose symptoms do not decrease over time.

The role of N-terminal heterocycles in hydrogen bonding to α-chymotrypsin.

A series of dipeptide aldehydes containing different N-terminal heterocycles was prepared and assayed in vitro against α-chymotrypsin to ascertain the importance of the heterocycle in maintaining a ß-strand geometry while also providing a hydrogen bond donor equivalent to the backbone amide nitrogen of the surrogate amino acid. The dipeptide containing a pyrrole constraint (10) was the most potent inhibitor, with >30-fold improved activity over dipeptides which lacked a nitrogen hydrogen bond donor (namely thiophene 11, furan 12 and pyridine 13). Molecular docking studies of 10 bound to α-chymotrypsin demonstrates a hydrogen bond between the pyrrole nitrogen donor and the backbone carbonyl of Gly216 located in the S3 pocket which is proposed to be critical for overall binding.

Exploring the gold-standard: Evidence for a two-factor model of the Clinician Administered PTSD Scale for the DSM-5.

OBJECTIVE: The latent factor structure of posttraumatic stress disorder (PTSD) remains a source of considerable variability. The current study compared several a priori factor structures, as well as a novel 2-factor structure of posttraumatic psychological distress as measured by the Clinician Administered PTSD scale for the DSM-5 (CAPS-5). In addition, variability in diagnostic rates according to the divergent DSM-5 and ICD-11 criteria were explored. METHOD: The setting for this study was a Level 1 trauma center in a U.S. metropolitan city. Data were pooled from 2 studies (N = 309) and participants were administered the CAPS-5 at 1 (n = 139) or 6 months postinjury (n = 170). Confirmatory factor analysis (CFA) was used to compare several factor models, and prevalence rates based on DSM-5 and ICD-11 criteria were compared via z tests and kappa. RESULTS: CFAs of 5 factor structures indicated good fit for all models. A novel 2-factor model based on competing models of PTSD symptoms and modification indices was then tested. The 2-factor model of the CAPS-5 performed as well or better on most indices compared to a 7-factor hybrid. Comparisons of PTSD prevalence rates found no significant differences, but agreement was variable. CONCLUSIONS: These findings indicate that the CAPS-5 can be seen as measuring 2 distinct phenomena: posttraumatic stress disorder and general posttraumatic dysphoria. This is an important contribution to the current debate on which latent factors constitute PTSD and may reduce discordance. (PsycINFO Database Record