Investigating the reaction and substrate preference of indole-3-acetaldehyde dehydrogenase from the plant pathogen Pseudomonas syringae PtoDC3000.

Aldehyde dehydrogenases (ALDHs) catalyze the conversion of various aliphatic and aromatic aldehydes into corresponding carboxylic acids. Traditionally considered as housekeeping enzymes, new biochemical roles are being identified for members of ALDH family. Recent work showed that AldA from the plant pathogen Pseudomonas syringae strain PtoDC3000 (PtoDC3000) functions as an indole-3-acetaldehyde dehydrogenase for the synthesis of indole-3-acetic acid (IAA). IAA produced by AldA allows the pathogen to suppress salicylic acid-mediated defenses in the model plant Arabidopsis thaliana. Here we present a biochemical and structural analysis of the AldA indole-3-acetaldehyde dehydrogenase from PtoDC3000. Site-directed mutants targeting the catalytic residues Cys302 and Glu267 resulted in a loss of enzymatic activity. The X-ray crystal structure of the catalytically inactive AldA C302A mutant in complex with IAA and NAD+ showed the cofactor adopting a conformation that differs from the previously reported structure of AldA. These structures suggest that NAD+ undergoes a conformational change during the AldA reaction mechanism similar to that reported for human ALDH. Site-directed mutagenesis of the IAA binding site indicates that changes in the active site surface reduces AldA activity; however, substitution of Phe169 with a tryptophan altered the substrate selectivity of the mutant to prefer octanal. The present study highlights the inherent biochemical versatility of members of the ALDH enzyme superfamily in P. syringae.

Mapping the Trends of Kawasaki Disease in Hawai'i from 1996 to 2018.

Kawasaki disease is a systemic vasculitis of unknown etiology and is the leading cause of acquired heart disease in children in the developed world. Historically, Hawai'i has had the highest incidence of Kawasaki disease in the United States, likely due to the population's unique ancestral composition. To analyze the epidemiology, demographics and spatiotemporal distribution of Kawasaki disease in Hawai'i, a retrospective chart review was conducted utilizing data from Kapi'olani Medical Center for Women and Children encompassing the period of 1996-2018. A total of 858 patients were analyzed with 877 episodes of Kawasaki disease. On average, 37 episodes of Kawasaki disease were diagnosed annually over the 23-year period. The annual incidence was 32 per 100 000 children <5 years of age. Asian children (66.1%) accounted for the majority of cases, followed by Native Hawaiians and Other Pacific Islanders (16.6%). Unlike Japan and the continental United States, there was no characteristic seasonal pattern in the distribution of Kawasaki disease in Hawai'i, which may be attributed to its tropical climate or the recent changes in global weather patterns. Local geographical differences in the incidence of Kawasaki disease demonstrated that the Windward (Eastern) coast of O'ahu had a higher rate, while the Leeward (Western) coast displayed a lower incidence rate. This could be explained by variations in ethnic composition and weather patterns of certain areas. Future studies could provide geographical weather data and statistical analysis to determine what environmental triggers are correlated with Kawasaki disease trends in the State of Hawai'i.

Hypoxia-selective allosteric destabilization of activin receptor-like kinases: A potential therapeutic avenue for prophylaxis of heterotopic ossification.

Heterotopic ossification (HO), the pathological extraskeletal formation of bone, can arise from blast injuries, severe burns, orthopedic procedures and gain-of-function mutations in a component of the bone morphogenetic protein (BMP) signaling pathway, the ACVR1/ALK2 receptor serine-threonine (protein) kinase, causative of Fibrodysplasia Ossificans Progressiva (FOP). All three ALKs (-2, -3, -6) that play roles in bone morphogenesis contribute to trauma-induced HO, hence are well-validated pharmacological targets. That said, development of inhibitors, typically competitors of ATP binding, is inherently difficult due to the conserved nature of the active site of the 500+ human protein kinases. Since these enzymes are regulated via inherent plasticity, pharmacological chaperone-like drugs binding to another (allosteric) site could hypothetically modulate kinase conformation and activity. To test for such a mechanism, a surface pocket of ALK2 kinase formed largely by a key allosteric substructure was targeted by supercomputer docking of drug-like compounds from a virtual library. Subsequently, the effects of docked hits were further screened in vitro with purified recombinant kinase protein. A family of compounds with terminal hydrogen-bonding acceptor groups was identified that significantly destabilized the protein, inhibiting activity. Destabilization was pH-dependent, putatively mediated by ionization of a histidine within the allosteric substructure with decreasing pH. In vivo, nonnative proteins are degraded by proteolysis in the proteasome complex, or cellular trashcan, allowing for the emergence of therapeutics that inhibit through degradation of over-active proteins implicated in the pathology of diseases and disorders. Because HO is triggered by soft-tissue trauma and ensuing hypoxia, dependency of ALK destabilization on hypoxic pH imparts selective efficacy on the allosteric inhibitors, providing potential for safe prophylactic use.

Tailoring ultrasound-induced growth of perylene diimide nanowire crystals from solution by modification with poly(3-hexyl thiophene).

Tailoring nanocrystalline morphologies of organic semiconductors holds importance for organic electronics due to the influence of crystal characteristics on optoelectronic properties. Soluble additives that control crystal growth are commonly found in a variety of contexts such as biomineralization, pharmaceutical processing, and food science, while the use of ultrasound to modify crystal nucleation and growth has been routinely employed in producing crystals of food ingredients, biomolecules, pharmaceuticals, and inorganic materials. However, both methods have been applied to the growth of organic semiconductor crystals only in limited fashion. Here, we combine these two approaches to show that colloidally stable nanowire suspensions of a n-type small molecule, perylene diimide (PDI), can be prepared with well-controlled structures by sonocrystallization in the presence of a p-type polymer, poly(3-hexyl thiophene) (P3HT), as a soluble additive. By preferentially adsorbing on lateral crystal faces, P3HT dramatically reduces PDI crystal growth rate in the lateral directions relative to that along the nanowire axis, yielding nanocrystals with widths below 20 nm and narrow width distributions. With the use of uniform short PDI nanowires as seeds and extension with metastable solutions, controlled growth of PDI nanowires by "living crystallization" is demonstrated, providing access to narrowed length distributions and tailored branched crystal morphologies.

Template-directed self-assembly by way of molecular recognition at the micellar-solvent interface: modulation of the critical micelle concentration.

By incorporating the concepts of structural preorganisation and complementarity in concert with non-covalent donor-acceptor [ππ] and hydrophobic interactions, a duo of π-electron deficient bipyridinium-based linear and gemini amphiphiles capable of responding to molecular templation have been designed and synthesised. When combined with π-electron rich di(ethylene glycol)-disubstituted 1,5-dihydroxynaphthalene, a dramatic decrease in the critical aggregation concentration by ≈66% was observed with concomitant increases in the hydrodynamic diameter, ζ-potential, and Langmuir surface pressures of the micellar solutions-thus enhancing the detergents' efficiency and effectiveness at lowering the surface tension of water. By employing a phase separation model that takes into account the degree of counterion binding to the micellar aggregate superstructure, the effects of donor-acceptor templation on the Gibb's free energy of micellisation (ΔG) for the amphiphiles was quantified. It was found that donor-acceptor templation was capable of lowering ΔG by up to 1.75 kcal mol(-1) at which point it was observed, while under the influence of molecular templation, that linear single hydrophobic tailed detergent molecules exhibit properties characteristic of double-tailed phospholipid-like gemini surfactants.