Structural features of influenza A virus panhandle RNA enabling the activation of RIG-I independently of 5′-triphosphate

Retinoic acid-inducible gene I (RIG-I) recognizes specific molecular patterns of viral RNAs for inducing type I interferon. The C-terminal domain (CTD) of RIG-I binds to double-stranded RNA (dsRNA) with the 5′-triphosphate (5′-PPP), which induces a conformational change in RIG-I to an active form. It has been suggested that RIG-I detects infection of influenza A virus by recognizing the 5′-triphosphorylated panhandle structure of the viral RNA genome. Influenza panhandle RNA has a unique structure with a sharp helical bending. In spite of extensive studies of how viral RNAs activate RIG-I, whether the structural elements of the influenza panhandle RNA confer the ability to activate RIG-I signaling has been poorly explored. Here, we investigated the dynamics of the influenza panhandle RNA in complex with RIG-I CTD using NMR spectroscopy and showed that the bending structure of the panhandle RNA negates the requirement of a 5′-PPP moiety for RIG-I activation.     

Anti-photoaging activities of Sorbaria kirilowii ethanol extract in UVB-damaged cells

Sorbaria kirilowii (Regel) Maxim, a plant found in China, Korea, Japan, and east of Europe, is a common herb used for traditional medicinal purposes. However, its ability to prevent photoaging has not been studied. In this study, we investigated the anti-photoaging functions of an ethanol extract (Sk-EE) of S. kirilowii (Regel) Maxim using human keratinocytes exposed to UVB. First, we analyzed the cytotoxicity of Sk-EE. Then, we determine the expression of genes related to inflammation, collagen degradation, and moisture retention. We also explored the anti-photoaging mechanism of Sk-EE by determining correlated signaling pathways and target molecules using reporter gene assays and immunoblotting analyses. Sk-EE treatment of cells increased hyaluronic acid synthase (HAS), filaggrin (FLG), and collagen type I alpha 1 (COL1A1) expression. Sk-EE dose-dependently inhibited the UVB-induced expression of matrix metalloproteinases (MMPs) 1, 2, 9 and cyclooxygenase (COX)-2 by blocking the activator protein (AP)-1 signaling pathway, in particular the phosphorylation of c-Jun N-terminal kinase (JNK), p38, and extracellular response kinase (ERK). In addition, c-Fos and c-Jun were targeted by Sk-EE. Our results indicate that Sk-EE has anti-inflammatory and skin-protective properties, and could be a candidate to treat signs of photoaging.     

A short-term response of macroalgae to potential competitor removal in a mid-intertidal habitat in Korea

Interspecific interactions among three dominant macroalgae, Pterocladia capillacea (Rhodophyta), Hizikia fusiformis (Heterokontophyta) and Chondracanthus intermedius (Rhodophyta), were experimentally investigated on the rocky mid-intertidal zone of Sungsan, Jeju Island, Korea from March 1998 to June 1999. Each of the potentially competing species was removed in permanent plots (20 × 20 cm), and percent covers of non-manipulated species were measured by an image analyzing method using a digital camera. Pterocladia capillacea was the most abundant during all seasons, except for winter. Its abundance was lowered by the removal of the turf-forming alga C. intermedius, indicating that turf had a positive effect on P. capillacea. Conversely, there was a negative effect of P. capillacea on the abundance of C. intermedius. Interactions between C. intermedius and P. capillacea can probably be explained as a consequence of the water-trapping ability of the former and the canopy-forming ability of the latter. There was, however, no apparent effect related to H. fusiformis since the abundance of this alga remained low. This study supports that both negative and positive effects between same pair of species could be common depending on the morphological differences of algae and particular habitat conditions.     

Conversion of levulinic acid to 2-butanone by acetoacetate decarboxylase from Clostridium acetobutylicum

In this study, a novel system for synthesis of 2-butanone from levulinic acid (γ-keto-acid) via an enzymatic reaction was developed. Acetoacetate decarboxylase (AADC; E.C. 4.1.1.4) from Clostridium acetobutylicum was selected as a biocatalyst for decarboxylation of levulinic acid. The purified recombinant AADC from Escherichia coli successfully converted levulinic acid to 2-butanone with a conversion yield of 8.4–90.3 % depending on the amount of AADC under optimum conditions (30 °C and pH 5.0) despite that acetoacetate, a β-keto-acid, is a natural substrate of AADC. In order to improve the catalytic efficiency, an AADC-mediator system was tested using methyl viologen, methylene blue, azure B, zinc ion, and 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) as mediators. Among them, methyl viologen showed the best performance, increasing the conversion yield up to 6.7-fold in comparison to that without methyl viologen. The results in this study are significant in the development of a renewable method for the synthesis of 2-butanone from biomass-derived chemical, levulinic acid, through enzymatic decarboxylation.     

The Genome Sequence of a Type ST239 Methicillin-Resistant Staphylococcus aureus Isolate from a Malaysian Hospital

We report the genome sequence of a healthcare-associated MRSA type ST239 clone isolated from a patient with septicemia in Malaysia. This clone typifies the characteristics of ST239 lineage, including resistance to multiple antibiotics and antiseptics.     

Macular Ganglion Cell Analysis Determined by Cirrus HD Optical Coherence Tomography for Early Detecting Chiasmal Compression

PurposeTo evaluate the performance of macular ganglion cell-inner plexiform layer (mGCIPL) measurement with Cirrus high-definition (HD) optical coherence tomography (OCT) for early detection of optic chiasmal compression.MethodsForty-six eyes of 46 patients with optic chiasmal compression caused by a pituitary adenoma (PA group), 31 eyes of 31 patients with normal tension glaucoma (NTG group), and 32 eyes of 32 normal participants (control group) were enrolled. The PA group was subdivided into two subgroups, which comprised patients with temporal visual field (VF) defects (perimetric PA group, 34 eyes) and without VF defect (preperimetric PA group, 12 eyes). The mGCIPL thickness and circumpapillary retinal nerve fiber layer (cpRNFL) thickness were measured using Cirrus HD-OCT. We calculated the number of patients who had an abnormal GCA sector map, defined as at least one yellow or red sector.ResultsEyes in the perimetric PA group had significantly decreased mGCIPL thickness in all sectors. Eyes in the preperimetric PA group had significantly thinner mGCIPL in the superior, superonasal, inferonasal, and inferior sectors than eyes in control group, but no changes in cpRNFL parameters were observed. The mGCIPL thickness in inferonasal area showed the greatest AUC value (0.965), followed by the superonasal area (0.958) for discriminating preperimetric PA group from the control group. A higher reduction rate of mGCIPL thickness was noted in the nasal sector compared to other sectors, which was irrespective of temporal visual field defects. The mGCIPL thickness maps showed superonasal (P = 0.003) and inferonasal thinning in the PA group (P = 0.003), while inferotemporal thinning was revealed in the NTG group (P = 0.001).ConclusionsMacular GCIPL thickness parameters obtained with the Cirrus HD-OCT were useful in early detection of chiasmal compression and differentiating from NTG by characteristic nasal mGCIPL thinning.     

Identification of the yqhE and yafB genes encoding two 2, 5-diketo-D-gluconate reductases in Escherichia coli.

The identification of a gene (yiaE) encoding 2-ketoaldonate reductase (2KR) in our previous work led to the hypothesis that Escherichia coli has other ketogluconate reductases including 2, 5-diketo-D-gluconate reductase (25DKGR) and to study of the related ketogluconate metabolism. By using the deduced amino acid sequences of 5-diketo-D-gluconate reductase (5KDGR) of Gluconobacter oxydans and 25DKGR of Corynebacterium sp., protein databases were screened to detect homologous proteins. Among the proteins of E. coli, an oxidoreductase encoded by yjgU and having 56% similarity to 5KDGR of G. oxydans and two hypothetical oxidoreductases encoded by yqhE and yafB and having 49.8 and 42% similarity, respectively, to 25DKGR of Corynebacterium sp. were detected. Recently, the yjgU gene was identified as encoding 5KDGR and renamed idnO (C. Bausch, N. Peekhaus, C. Utz, T. Blais, E. Murray, T. Lowary, and T. Conway, J. Bacteriol. 180:3704-3710, 1998). The pathways involved in the metabolism of ketogluconate by E. coli have been predicted by biochemical analysis of purified enzymes and chemical analysis of the pathway intermediates. The gene products of yqhE and yafB were identified as 25DKGR-A, and 25DKGR-B, respectively, catalyzing the reduction of 25KDG to 2-keto-L-gulonate (2KLG). The native 25DKGR-A, 25DKGR-B, and 5KDGR had apparent molecular weights of about 30,000, 30,000, and 54,000, respectively. In sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels, all three enzymes showed protein bands with a molecular weight of about 29,000, which indicated that 25DKGR-A, 25DKGR-B, and 5KDGR may exist as monomeric, monomeric, and dimeric proteins, respectively. The optimum pHs for reduction were 7.5, 7.0, and 8.0, respectively. The 5KDGR was active with NADH, whereas 25DKGR-A and 25DKGR-B were active with NADPH as a preferred electron donor. 25DKG can be converted to 5KDG by 2KR, which is then reduced to D-gluconate by 5KDGR. The pathways were compared with those of Erwinia sp. and Corynebacterium sp. A BLAST search of published and incomplete microbial genome sequences revealed that the ketogluconate reductases and their related metabolism may be widespread in many species.