Aly and THO are required for assembly of the human TREX complex and association of TREX components with the spliced mRNA

The mRNA export complex TREX (TREX) is known to contain Aly, UAP56, Tex1 and the THO complex, among which UAP56 is required for TREX assembly. Here, we systematically investigated the role of each human TREX component in TREX assembly and its association with the mRNA. We found that Tex1 is essentially a subunit of the THO complex. Aly, THO and UAP56 are all required for assembly of TREX, in which Aly directly interacts with THO subunits Thoc2 and Thoc5. Both Aly and THO function in linking UAP56 to the cap-binding protein CBP80. Interestingly, association of UAP56 with the spliced mRNA, but not with the pre-mRNA, requires Aly and THO. Unexpectedly, we found that Aly and THO require each other to associate with the spliced mRNA. Consistent with these biochemical results, similar to Aly and UAP56, THO plays critical roles in mRNA export. Together, we propose that Aly, THO and UAP56 form a highly integrated unit to associate with the spliced mRNA and function in mRNA export.     

Expression of antimicrobial peptides thanatin(S) in transgenic Arabidopsis enhanced resistance to phytopathogenic fungi and bacteria

Thanatin(S) is an analog of thanatin, an insect antimicrobial peptide possessing strong and broad spectrum of antimicrobial activity. In order to investigate if the thanatin could be used in engineering transgenic plants for increased resistance against phytopathogens, the synthetic thanatin(S) was introduced into Arabidopsis thaliana plants. To increase the expression level of thanatin(S) in plants, the coding sequence was optimized by plant-preference codon. To avoid cellular protease degradation, signal peptide of rice Cht1 was fused to N terminal of thanatin(S) for secreting the expressed thanatin(S) into intercellular spaces. To evaluate the application value of thanatin(S) in plant disease control, the synthesized coding sequence of Cht1 signal peptide (Cht1SP)-thanatin(S) was ligated to plant gateway destination binary vectors pGWB11 (with FLAG tag). Meanwhile, in order to observe the subcellular localization of Cht1SP-thanatin(S)-GFP and thanatin(S)-GFP, the sequences of Cht1SP-thanatin(S) and thanatin(S) were respectively linked to pGWB5 (with GFP tag). The constructs were transformed into Arabidopsis ecotype Col-0 and mutant pad4-1 via Agrobacterium-mediated transformation. The transformants with Cht1SP-thanatin(S)-FLAG fusion gene were analyzed by genomic PCR, real-time PCR, and western blots and the transgenic Arabidopsis plants introduced respectively Cht1SP-thanatin(S)-GFP and thanatin(S)-GFP were observed by confocal microscopy. Transgenic plants expressing Cht1SP-thanatin(S)-FLAG fusion protein showed antifungal activity against Botrytis cinerea and powdery mildew, as well as antibacterial activity against Pseudomonas syringae pv. tomato. And the results from confocal observation showed that the GFP signal from Cht1SP-thanatin(S)-GFP transgenic Arabidopsis plants occurred mainly in intercellular space, while that from thanatin(S)-GFP transgenic plants was mainly detected in the cytoplasm and that from empty vector transgenic plants was distributed uniformly throughout the cell, demonstrating that Cht1 signal peptide functioned. In addition, thanatin(S) and thanatin(S)-FLAG chemically synthesized have both in vitro antimicrobial activities against P. syringae pv. tomato and B. cinerea. So, thanatin(S) is an ideal candidate AMPs for the construction of transgenic crops endowed with a broad-spectrum resistance to phytopathogens and the strategy is feasible to link a signal peptide to the target gene.     

Cloning of the Lentinula edodes B mating-type locus and identification of the genetic structure controlling B mating

During the life cycle of heterothallic tetrapolar Agaricomycetes such as Lentinula edodes (Berk.) Pegler, the mating type system, composed of unlinked A and B loci, plays a vital role in controlling sexual development and resulting formation of the fruit body. L. edodes is produced worldwide for consumption and medicinal purposes, and understanding its sexual development is therefore of great importance. A considerable amount of mating type factors has been indicated over the past decades but few genes have actually been identified, and no complete genetic structures of L. edodes B mating-type loci are available. In this study, we cloned the matB regions from two mating compatible L. edodes strains, 939P26 and 939P42. Four pheromone receptors were identified on each new matB region, together with three and four pheromone precursor genes in the respective strains. Gene polymorphism, phylogenetic analysis and distribution of pheromone receptors and pheromone precursors clearly indicate a bipartite matB locus, each sublocus containing a pheromone receptor and one or two pheromone precursors. Detailed sequence comparisons of genetic structures between the matB regions of strains 939P42, 939P26 and a previously reported strain SUP2 further supported this model and allowed identification of the B mating type subloci borders. Mating studies confirmed the control of B mating by the identified pheromone receptors and pheromones in L. edodes.     

Sedum plumbizincicola X.H. Guo et S.B. Zhou ex L.H. Wu (Crassulaceae): a new species from Zhejiang Province, China

Sedum plumbizincicola X.H. Guo et S.B. Zhou ex L.H. Wu (Crassulaceae), a new species restricted to lead–zinc mining areas in Zhejiang Province, China, is described and illustrated. This taxon belongs to sect. Sedum (H. Ohba) S.H. Fu based on the adaxially gibbous carpels and follicles. It superficially resembles S. alfredii Hance and three other Sedum species found in the same area, but differs from these other taxa in bearing 4-merous flowers. Differences in geographical distribution, growth habit, phenology, macromorphology, leaf and stem anatomy, as well as seed micromorphology among S. plumbizincicola, S. alfredii and other related taxa in the genus Sedum are also reported. nrDNA internal transcribed spacers (ITS) sequences from seven populations of S. plumbizincicola support the recognition of this as a taxonomic entity distinct from S. alfredii.     

Structural divergence is more extensive than sequence divergence for a family of intrinsically disordered proteins

The p53 transactivation domain (p53TAD) is an intrinsically disordered protein (IDP) domain that undergoes coupled folding and binding when interacting with partner proteins like the E3 ligase, MDM2, and the 70 kDa subunit of replication protein A, RPA70. The secondary structure and dynamics of six closely related mammalian homologues of p53TAD were investigated using nuclear magnetic resonance (NMR) spectroscopy. Differences in both transient secondary structure and backbone dynamics were observed for the homologues. Many of these differences were localized to the binding sites for MDM2 and RPA70. The amount of transient helical secondary structure observed for the MDM2 binding site was lower for the dog and mouse homologues, compared with human, and the amount of transient helical secondary structure observed for the RPA70 binding site was higher for guinea pig and rabbit, compared with human. Differences in the amount of transient helical secondary structure observed for the MDM2 binding site were directly related to amino acid substitutions occurring on the solvent exposed side of the amphipathic helix that forms during the p53TAD/MDM2 interaction. Differences in the amount of transient helical secondary structure were not as easily explained for the RPA70 binding site because of its extensive sequence divergence. Clustering analysis shows that the divergence in the transient secondary structure of the p53TAD homologues exceeds the amino acid sequence divergence. In contrast, strong correlations were observed between the backbone dynamics of the homologues and the sequence identity matrix, suggesting that the dynamic behavior of IDPs is a conserved evolutionary feature. Proteins 2013; 81:1686–1698. © 2013 Wiley Periodicals, Inc.     

Salvianolic acid B inhibits the amyloid formation of human islet amyloid polypeptideand protects pancreatic beta‐cells against cytotoxicity

The misfolding of human islet amyloid polypeptide (hIAPP) is regarded as one of the causative factors of type 2 diabetes mellitus (T2DM). Salvia miltiorrhiza (Danshen), one of the most commonly used of traditional Chinese medicines, is often used in Compound Recipes for treating diabetes, however with unclear mechanisms. Since salvianolic acid B (SalB) is the most abundant bioactive ingredient of salvia miltiorrhiza water‐extract. In this study, we tested whether SalB has any effect on the amyloidogenicity of hIAPP. Our results clearly suggest that SalB can significantly inhibit the formation of hIAPP amyloid and disaggregate hIAPP fibrils. Furthermore, photo‐crosslinking based oligomerization studies suggest SalB significantly suppresses the toxic oligomerization of hIAPP monomers. Cytotoxicity protection effects on pancreatic INS‐1 cells by SalB were also observed using MTT‐based assays, potentially due to the inhibition on the membrane disruption effects and attenuated mitochondria impairment induced by hIAPP. These results provide evidence that SalB may further be studied on the possible pharmacological treatment for T2DM. Proteins 2013. © 2012 Wiley Periodicals, Inc.     

Antimicrobial and antifouling polymeric coating mitigates persistence of Pseudomonas aeruginosa biofilm

Abstract

Food wasted due to food spoilage remains a global challenge to the environmental sustainability and security of food supply. In food manufacturing, post-processing contamination of food can occur due to persistent bacterial biofilms, which can be resistant to conventional cleaning and sanitization. The objective was to characterize the efficacy of a polymeric coating in reducing Pseudomonas aeruginosa biofilm establishment and facilitating its removal. Viable cell density of a 48?h biofilm was reduced by 2.10 log cfu cm^?2 on the coated surface, compared to native polypropylene. Confocal laser scanning and electron microscopy indicated reductions in mature biofilm viability and thickness on the coated material. The antifouling coating improved cleanability, with ～2.5 log cfu cm^?2 of viable cells remaining after 105?min cleaning by water at 65?°C, compared to 4.5 log cfu cm^?2 remaining on native polypropylene. Such coatings may reduce the persistence of biofilms in food processing environments, in support of reducing food spoilage and waste     

Dissipative particle dynamics simulation on the meso-scale structure of diblock copolymer under cylindrical confinement

The meso-scale structure of symmetric diblock copolymer under cylindrical confinement is studied by dissipative particle dynamics (DPD). The simulation results show that coiled cylindrical geometry is favored in the presence of larger cylinder radius (R/L ₀>～1.5), and the number of rings depends on the cylinder radius. Because of the cylinder wall's selectivity, each block can form the central core, but only the preferential block forms the outmost layer. An approximately linear relationship exists between structure transition point, which is approximately in proportion to the 3/5 exponential of chain length of copolymer and number of layers. As the cylinder radius is decreased, a helical morphology is found. Lamellae parallel to the underside of the cylinder appear when the cylinder radius is made smaller (R/L ₀ < ～1.1).