Structural and sequence comparisons of bacterial enoyl-CoA isomerase and enoyl-CoA hydratase

Crystal structures of enoyl-coenzyme A (CoA) isomerase from Bosea sp. PAMC 26642 (BoECI) and enoyl-CoA hydratase from Hymenobacter sp. PAMC 26628 (HyECH) were determined at 2.35 and 2.70 Å resolution, respectively. BoECI and HyECH are members of the crotonase superfamily and are enzymes known to be involved in fatty acid degradation. Structurally, these enzymes are highly similar except for the orientation of their C-terminal helix domain. Analytical ultracentrifugation was performed to determine the oligomerization states of BoECI and HyECH revealing they exist as trimers in solution. However, their putative ligand-binding sites and active site residue compositions are dissimilar. Comparative sequence and structural analysis revealed that the active site of BoECI had one glutamate residue (Glu135), this site is occupied by an aspartate in some ECIs, and the active sites of HyECH had two highly conserved glutamate residues (Glu118 and Glu138). Moreover, HyECH possesses a salt bridge interaction between Glu98 and Arg152 near the active site. This interaction may allow the catalytic Glu118 residue to have a specific conformation for the ECH enzyme reaction. This salt bridge interaction is highly conserved in known bacterial ECH structures and ECI enzymes do not have this type of interaction. Collectively, our comparative sequential and structural studies have provided useful information to distinguish and classify two similar bacterial crotonase superfamily enzymes.     

Sequence analysis of the first B5 subgenogroup strain of enterovirus 71 isolated in Korea

Journal of Microbiology - Enterovirus A71 (EV71), the main etiological agent of handfoot- mouth disease (HFMD), circulates in many areas of the world and has caused large epidemics since 1997,...     

Peroxiredoxin 2 deficiency reduces white adipogenesis due to the excessive ROS generation

Reactive oxygen species (ROS) act as signaling molecules to regulate various cell functions. Numerous studies have demonstrated ROS to be essential for the differentiation of adipocytes. Peroxiredoxins (Prxs) are a ubiquitous family of antioxidant enzymes in mammalian cells. Prx2 is present in the cytoplasm and cell membranes and demonstrates ROS scavenging activity. We focused on Prx2 involvement in regulating adipogenesis and lipid accumulation and demonstrated that Prx2 expression was upregulated during adipocyte differentiation. In addition, the silencing of Prx2 (shPrx2) inhibited adipogenesis by modulating adipogenic gene expression, and cell death was enhanced via increased ROS production in shPrx2‐3T3‐L1 cells. These results demonstrate that shPrx2 triggers adipocyte cell death and weakens adipocyte function via ROS production. Taken together, our data suggest the participation of Prx2 in adipocyte function and differentiation. Our results also imply that the downregulation of Prx2 activity could help prevent obesity. Overall, findings support the development of ROS‐based therapeutic solutions for the treatment of obesity and obesity‐related metabolic disorders.     

Evolutionary processes of melanomas from giant congenital melanocytic nevi

Melanoma can develop in a congenital melanocytic nevus (CMN). In fact, a large CMN is associated with a high risk of developing melanoma. Although melanomas arising from CMNs are thought to have a pathogenesis distinct from conventional melanomas, no studies have been conducted on the evolution or tumor heterogeneity of CMN melanomas. We applied multi‐region whole‐exome sequencing to investigate the clonal nature of driver events and evolutionary processes in CMNs and melanomas arising from CMNs. In two patients, we observed an independent subclonal evolution in cancerized fields of CMNs and chromosome 8q amplification in both melanomas arising from CMNs. The amplification of MYC, located in chromosome 8q, was correlated with the percentage of tumor cells expressing high levels of MYC protein detected in melanoma cells by immunohistochemistry. Our analysis suggests that each CMN cell may evolve sporadically and that amplification of MYC might be a key event for melanoma development in CMNs.     

Insecticidal and insect growth regulatory activities of secondary metabolites from entomopathogenic fungi,Lecanicillium attenuatum

Insect growth regulators (IGRs) are effective alternatives to chemical insecticides because of their specificity and low environmental toxicity. Entomopathogenic fungi are an important natural pathogen of insects and have been developed as biological control agents. They produce a wide range of secondary metabolites such as antibiotics, pesticides, growth-promoting or inhibiting compounds and insect attracting agents. In this study, to explore novel IGR substances from entomopathogenic fungi, culture extracts of 189 entomopathogenic fungi isolated from Korean soil samples were investigated for their juvenile hormone (JH)-based IGR activities. Whereas none of the culture extracts exhibited JH agonist (JHA) activity, 14 extracts showed high levels of JH antagonist (JHAN) activity. Among them, culture extract of JEF-145 strain, which was identified as Lecanicillium attenuatum, showed the highest insecticidal against Aedes albopictus and Plutella xylostella. At liquid culture condition, JHAN activity was observed in culture soup rather than mycelial cake, indicating that substances with JHAN activity are released from the JEF-145 strain during culture. Furthermore, while extract from solid cultured JEF-145 strain showed insecticidal activities against both A. albopictus and P. xylostella, that from liquid cultured fungi showed insecticidal activity only against A. albopictus, indicating that L. attenuatum JEF-145 strain produces different kinds of secondary metabolites with JHAN activity depending on culture conditions. These results suggested that JHAN substances derived from entomopathogenic fungi could be usefully exploited to develop novel eco-friendly IGR insecticides.     

Arabidopsis RING E3 ubiquitin ligase JUL1 participates in ABA‐mediated microtubule depolymerization,stomatal closure,and tolerance response to drought stress

Ubiquitination is a critical post‐translational protein modification that has been implicated in diverse cellular processes, including abiotic stress responses, in plants. In the present study, we identified and characterized a T‐DNA insertion mutant in the At5g10650 locus. Compared to wild‐type Arabidopsis plants, at5g10650 progeny were hyposensitive to ABA at the germination stage. At5g10650 possessed a single C‐terminal C3HC4‐type Really Interesting New Gene (RING) motif, which was essential for ABA‐mediated germination and E3 ligase activity in vitro. At5g10650 was closely associated with microtubules and microtubule‐associated proteins in Arabidopsis and tobacco leaf cells. Localization of At5g10650 to the nucleus was frequently observed. Unexpectedly, At5g10650 was identified as JAV1‐ASSOCIATED UBIQUITIN LIGASE1 (JUL1), which was recently reported to participate in the jasmonate signaling pathway. The jul1 knockout plants exhibited impaired ABA‐promoted stomatal closure. In addition, stomatal closure could not be induced by hydrogen peroxide and calcium in jul1 plants. jul1 guard cells accumulated wild‐type levels of H₂O₂ after ABA treatment. These findings indicated that JUL1 acts downstream of H₂O₂ and calcium in the ABA‐mediated stomatal closure pathway. Typical radial arrays of microtubules were maintained in jul1 guard cells after exposure to ABA, H₂O₂, and calcium, which in turn resulted in ABA‐hyposensitive stomatal movements. Finally, jul1 plants were markedly more susceptible to drought stress than wild‐type plants. Overall, our results suggest that the Arabidopsis RING E3 ligase JUL1 plays a critical role in ABA‐mediated microtubule disorganization, stomatal closure, and tolerance to drought stress.     

Serum biomarker discovery related to pathogenesis in acute coronary syndrome by proteomic approach

Acute coronary syndrome (ACS) results from inadequate supply of blood flow from the coronary arteries to the heart or ischemia. ACS has an extremely high morbidity and mortality. The levels of biomarkers currently used for detection of ACS also increase in response to myocardial necrosis and other diseases and are not elevated immediately after symptoms appear, thus limiting their diagnostic capacity. Therefore, we aimed to discover new ACS diagnostic biomarkers with high sensitivity and specificity that are specifically related to ACS pathogenesis. Sera from 50 patients with ACS and healthy controls (discovery cohort) each were analyzed using mass spectrometry (MS) to identify differentially expressed proteins, and protein candidates were evaluated as ACS biomarkers in 120 people in each group (validation cohort). α-1-acid glycoprotein 1 (AGP1), complement C5 (C5), leucine-rich α-2-glycoprotein (LRG), and vitronectin (VN) were identified as biomarkers whose levels increase and gelsolin (GSN) as a biomarker whose levels decrease in patients with ACS. We concluded that these biomarkers are associated with the pathogenesis of ACS and can predict the onset of ACS prior to the appearance of necrotic biomarkers.