Structure of catalytic domain of Matriptase in complex with Sunflower trypsin inhibitor-1

Seed storage proteins are both an important source of nutrition for humans and essential for seedling establishment. Interestingly, unusual napin-type 2S seed storage albumin precursors in sunflowers contain a sequence that is released as a macrocyclic peptide during post-translational processing. The mechanism by which such peptides emerge from linear precursor proteins has received increased attention; however, the structural characterization of intact precursor proteins has been limited. Here, we report the 3D NMR structure of the Helianthus annuus PawS1 (preproalbumin with sunflower trypsin inhibitor-1) and provide new insights into the processing of this remarkable dual-destiny protein. In seeds, PawS1 is matured by asparaginyl endopeptidases (AEPs) into the cyclic peptide SFTI-1 (sunflower trypsin inhibitor-1) and a heterodimeric 2S albumin. The structure of PawS1 revealed that SFTI-1 and the albumin are independently folded into well-defined domains separated by a flexible linker. PawS1 was cleaved in vitro with recombinant sunflower HaAEP1 and in situ using a sunflower seed extract in a way that resembled the expected in vivo cleavages. Recombinant HaAEP1 cleaved PawS1 at multiple positions, and in situ, its flexible linker was removed, yielding fully mature heterodimeric albumin. Liberation and cyclization of SFTI-1, however, was inefficient, suggesting that specific seed conditions or components may be required for in vivo biosynthesis of SFTI-1. In summary, this study has revealed the 3D structure of a macrocyclic precursor protein and provided important mechanistic insights into the maturation of sunflower proalbumins into an albumin and a macrocyclic peptide

Experimental Study of Broadcatching in BitTorrent

Abstract—Broadcatching is a promising mechanism to improve the experience of BitTorrent users by automatically downloading files advertised through RSS feeds. However, though widely used, the mechanism itself has not been well studied. In this paper, we conducted extensive experiments on PlanetLab to evaluate the performance of Broadcatching under different typical scenarios. The results demonstrated the effectiveness of the Broadcatching: it reduces the average completion time and downloading failure ratio. It also improves the overall fairness of the system: the subscribers are encouraged to share more while downloading faster, which results in the increased share ratio. Our study is the first work to systematically evaluate the benefit of Broadcatching and sheds lights on how to improve performance of BitTorrrent by manipulating peer’s behavior like Broadcatching. I

Synthesis and self-assembly of tetraphenylethene and biphenyl based AIE-active triazoles

Self-assembly of fluorescent functional materials has attracted increasing interest in the fabrication of optoelectronic and biological nanodevices. Tetraphenylethene (TPE) is a typical dye molecule with aggregation-induced-emission (AIE) characteristics. Melding TPE carrying triple-bond functionality with diazide-containing biphenyl through ''click'' chemistry generates AIE-active luminogens [1,1'-biphenyl]-4,4'-diyl bis(6-(4-(4-(1,2,2-triphenylvinyl)phenyl)-1H-1,2,3-triazol-1-yl) hexanoate) [1(5)] and[1,1'-biphenyl]-4,4'-diyl bis(11-(4-(4-(1,2,2-triphenylvinyl)phenyl)-1H-1,2,3-triazol-1-yl) undecanoate)[1(10)] with solid state efficiencies up to unity. Slow addition of dilute THF solutions of 1(m) (m ¼ 5, 10) into nonsolvents such as n-hexane and water yields self-assembled white wooly solids. TEM and SEM observations reveal the (helical) nanofibrous structure of the aggregates. Upon cooling from their concentrated hot solutions, 1(m) readily precipitate. Meanwhile, they can also form gels at high concentrations. Both precipitates and gels of 1(m) exhibit structures similar to those of the aggregates formed in nonsolvents. These results indicate that 1(m) can facilely self-assemble into high emission efficiency (helical) nanofibers, thus paving the way for their optoelectronic and biological applications

Visual exploration of sparse traffic trajectory data

In this paper, we present a visual analysis system to explore sparse traffic trajectory data recorded by transportation cells. Such data contains the movements of nearly all moving vehicles on the major roads of a city. Therefore it is very suitable for macro-traffic analysis. However, the vehicle movements are recorded only when they pass through the cells. The exact tracks between two consecutive cells are unknown. To deal with such uncertainties, we first design a local animation, showing the vehicle movements only in the vicinity of cells. Besides, we ignore the micro-behaviors of individual vehicles, and focus on the macro-traffic patterns. We apply existing trajectory aggregation techniques to the dataset, studying cell status pattern and inter-cell flow pattern. Beyond that, we propose to study the correlation between these two patterns with dynamic graph visualization techniques. It allows us to check how traffic congestion on one cell is correlated with traffic flows on neighbouring links, and with route selection in its neighbourhood. Case studies show the effectiveness of our system

Privacy-preserving targeted mobile advertising: Formal models and analysis

Targeted Mobile Advertising (TMA) has emerged as a significant driver of the Internet economy. Such systems give rise to interesting challenges: there is a need to balance privacy and utility; there is a need to guarantee that applications' access to resources is appropriate; and there is a need to ensure that the targeting of ads is effective. As many authors have argued, formal models are ideal vehicles for reasoning about privacy, as well as for reasoning about the relationship between privacy and utility. To this end, we describe how the formal notation Z has been used to develop formal models to underpin a prototype privacypreserving TMA system. We give consideration to how formal models can help in underpinning the prototype system, in analysing privacy in the context of targeted mobile advertising, and in allowing users to specify control of their personal information

Intracellular clusterin interacts with brain isoforms of the bridging integrator 1 and with the microtubule-associated protein Tau in Alzheimer's disease.

Sporadic or late-onset Alzheimer's disease (AD) is expected to affect 50% of individuals reaching 85 years of age. The most significant genetic risk factor for late-onset AD is the e4 allele of APOE gene encoding apolipoprotein E, a lipid carrier shown to modulate brain amyloid burden. Recent genome-wide association studies have uncovered additional single nucleotide polymorphisms (SNPs) linked to AD susceptibility, including those in the CLU and BIN1 genes encoding for clusterin (CLU) and the bridging integrator 1 (BIN1) proteins, respectively. Because CLU has been implicated in brain amyloid-β (Aβ) clearance in mouse models of amyloid deposition, we sought to investigate whether an AD-linked SNP in the CLU gene altered Aβ42 biomarker levels in the cerebrospinal fluid (CSF). Instead, we found that the CLU rs11136000 SNP modified CSF levels of the microtubule-associated protein Tau in AD patients. We also found that an intracellular form of CLU (iCLU) was upregulated in the brain of Tau overexpressing Tg4510 mice, but not in Tg2576 amyloid mouse model. By overexpressing iCLU and Tau in cell culture systems we discovered that iCLU was a Tau-interacting protein and that iCLU associated with brain-specific isoforms of BIN1, also recently identified as a Tau-binding protein. Through expression analysis of CLU and BIN1 variants, we found that CLU and BIN1 interacted via their coiled-coil motifs. In co-immunoprecipitation studies using human brain tissue, we showed that iCLU and the major BIN1 isoform expressed in neurons were associated with modified Tau species found in AD. Finally, we showed that expression of certain coding CLU variants linked to AD risk led to increased levels of iCLU. Together, our findings suggest that iCLU and BIN1 interaction might impact Tau function in neurons and uncover potential new mechanisms underlying the etiology of Tau pathology in AD

Monomer and dimer emissions in the solutions of a monosubstituted polyacetylene

Photoluminescence (PL) of tetrahydrofuran solutions of a monosubstituted polyacetylene with liquid crystalline pendants, poly(11-{[4′-heptoxy-4-biphenylyl)carbonyl]oxy}-1-undecyne) (1), has been investigated. Intense ultraviolet emission (∼370 nm) has been detected in its dilute solution (2.5 μM). As the solution becomes concentrated (up to 39 mM), the emission color changes to deep blue and finally to blue (∼430 nm). In addition to the large-scale red shift in PL peak, its luminescent intensity changes about two orders of magnitude. Based on the extended Hückel tight-binding calculations, the 370 nm peak is assigned to monomer emission, which originates from the biphenyl mesogen in the pendants, and the peak at 430 nm corresponds to dimer emission, which is related to the aggregates formed in concentrated solutions. Lyotropic mesophase was observed as 1 dissolves in tetrahydrofuran