The PorX/PorY system is a virulence factor of Porphyromonas gingivalis and mediates the activation of the type IX secretion system.

PorX/PorY is a two-component system (TCS) of Porphyromonas gingivalis that governs transcription of numerous genes including those encoding a type IX secretion system (T9SS) for gingipain secretion and heme accumulation. Here, an in vitro analysis showed that the response regulator PorX specifically bound to two regions in the promoter of porT, a known PorX-regulated T9SS gene, thus demonstrating that PorX/PorY can directly regulate specific target genes. A truncated PorX protein containing the N-terminal receiver and effector domains retained a wild-type ability in both transcription regulation and heme accumulation, ruling out the role of the C-terminal ALP domain in gene regulation. The PorX/PorY system was the only TCS essential for heme accumulation and concomitantly responded to hemin to stimulate transcription of several known PorX-dependent genes in a concentration-dependent manner. We found that PorX/PorY activated the sigH gene, which encodes a sigma factor known for P. gingivalis adaptation to hydrogen peroxide (H2O2). Consistently, both ΔporX and ΔsigH mutants were susceptible to H2O2, suggesting a PorX/PorY-σH regulatory cascade to confer resistance to oxidative stress. Furthermore, the ΔporX mutant became susceptible to high hemin levels that could induce oxidative stress. Therefore, a possible reason why hemin activates PorX/PorY is to confer resistance to hemin-induced oxidative stress. We also demonstrated that PorX/PorY was essential for P. gingivalis virulence because the ΔporX mutant was avirulent in a mouse model. Specifically, this TCS was required for the repression of proinflammatory cytokines secreted by dendritic cells and T cells in the P. gingivalis-infected mice.

A super-hydrophobic perfluoropolyether coated polytetrafluoroethylene sheets substrate for detection of acetamiprid surface-enhanced Raman spectroscopy.

In this paper, a hydrophobic substrate as concentrators including an inner layer of polytetrafluoroethylene (PTFE) and an outer layer covered a thin layer of perfluoropolyether (PFPE) was constructed to achieve a higher sensitivity for acetamiprid (AC) SERS detection. The condensation effect of the PTFE-PFPE hydrophobic substrate-induced aggregation of gold nanoparticles (Au NPs) result ''hot spots'' for SERS. The hydrophobic substrate is better reproducibility (RSD < 5%) compared with that on a conventional silicon wafer. A further application of the hydrophobic substrate was demonstrated by the detection of AC in tea samples within a detection range of 0.03 mg/L to 3 mg/L. The hydrophobic substrate eliminates the problem of solution diffusion to avoid the "coffee ring" effect (When a droplet adheres to a solid surface, the suspended molecular particles usually deposit on the edge of the droplet to form a ring).

TPGS-Modified Long-Circulating Liposomes Loading Ziyuglycoside I for Enhanced Therapy of Myelosuppression.

BACKGROUND: Ziyuglycoside I (ZgI), an active ingredient isolated from traditional Chinese medicine Sanguisorba officinalis L, has been demonstrated to increase the leucocytes and protect hematopoietic stem cells. However, the poor solubility and a short half-life of ZgI limit its bioavailability and efficacy. The D-α-tocopherol polyethylene glycol 1000 succinate (TPGS) has been widely used to increase the solubility, improve the encapsulation rate, and extend the half-life of drugs. METHODS: Here, we formulated the TPGS-modified long-circulating liposomes loading ZgI with a sustained drug release and enhanced therapy for myelosuppression. ZgI-TPGS-liposomes were manufactured using a thin-film hydration technique, followed by characterizations of physicochemical properties, including the particle size, zeta potential, TEM, SEM, FTIR, XRD, stability, drug loading (DL), encapsulation efficiency (EE). The in vitro and in vivo delivery efficiency were further evaluated by cellular uptake, in vitro drug release and in vivo pharmacokinetics. Finally, therapeutic effect on myelosuppression was investigated. RESULTS: The ZgI-TPGS-liposomes had an particle size of 97.89 ± 1.42 nm and ZP of -28.65 ± 0.16 mV. It exhibited DL of 9.06 ± 0.76% and EE of 92.34 ± 3.83%, along with excellent storage stability, cellular uptake and sustained drug release to free ZgI and liposomes without TPGS. Additionally, the TPGS modified liposomes significantly enhanced the therapeutic effect of ZgI on CTX induced myelosuppression, which can be confirmed in the apoptosis inhibition and cell viability promotion of CTX injured HSPC-1 cells. Also, the mice in vivo pharmacodynamics demonstrated that TPGS liposomes promoted ZgI increasing the numbers of leucocytes and neutrophils in myelosuppression mice induced by CTX. CONCLUSION: Our research suggest that TPGS-modified long-circulating liposomes loading ziyuglycoside I has potential application in myelosuppression therapy.

A PorX/PorY and σP Feedforward Regulatory Loop Controls Gene Expression Essential for Porphyromonas gingivalis Virulence.

The PorX/PorY two-component system in the periodontal pathogen Porphyromonas gingivalis controls the expression of the por genes, encoding a type IX secretion system, and the sigP gene, encoding sigma factor σP. Previous results implied that PorX/PorY and σP formed a regulatory cascade because the PorX/PorY-activated σP enhanced the por genes, including porT, via binding to their promoters. We recently showed that PorX also binds to the por promoters, thus suggesting that an alternative mechanism is required for the PorX/PorY- and σP-governed expression. Here, our in vitro assays show the PorX response regulator binds to the sigP promoter at a sequence shared with the porT promoter and enhances its transcription, mediated by a reconstituted P. gingivalis RNA polymerase holoenzyme. Merely producing σP in trans fails to reverse the porT transcription in a porX mutant, which further argues against the action of the proposed regulatory cascade. An in vitro transcription assay using a reconstituted RNA polymerase-σP holoenzyme verifies the direct role of PorX in porT transcription, since transcription is enhanced by a pure PorX protein. Accordingly, we propose that the PorX/PorY system coordinates with σP to construct a coherent regulatory mechanism, known as the feedforward loop. Specifically, PorX will not only bind to the sigP promoter to stimulate the expression of σP, but also bind to the porT promoter to facilitate the RNA polymerase-σP-dependent transcription. Importantly, mutations at the porX and sigP genes attenuate bacterial virulence in a mouse model, demonstrating that this regulatory mechanism is essential for P. gingivalis pathogenesis. IMPORTANCE The anaerobic bacterium Porphyromonas gingivalis is not only the major etiologic agent for chronic periodontitis, but also prevalent in some common noncommunicable diseases such as cardiovascular disease, Alzheimer's disease, and rheumatoid arthritis. We present genetic, biochemical, and biological results to demonstrate that the PorX/PorY two-component system and sigma factor σP build a specific regulatory network to coordinately control transcription of the genes encoding the type IX secretion system, and perhaps also other virulence factors. Results in this study verify that the response regulator PorX stimulates the expression of the genes encoding both σP and the type IX secretion system by binding to their promoters. This study also provides evidence that σP, like the PorX/PorY system, contributes to P. gingivalis virulence in a mouse model.