Leishmania actin binds and nicks kDNA as well as inhibits decatenation activity of type II topoisomerase

Leishmania actin (LdACT) is an unconventional form of eukaryotic actin in that it markedly differs from other actins in terms of its filament forming as well as toxin and DNase-1-binding properties. Besides being present in the cytoplasm, cortical regions, flagellum and nucleus, it is also present in the kinetoplast where it appears to associate with the kinetoplast DNA (kDNA). However, nothing is known about its role in this organelle. Here, we show that LdACT is indeed associated with the kDNA disc in Leishmania kinetoplast, and under in vitro conditions, it specifically binds DNA primarily through electrostatic interactions involving its unique DNase-1-binding region and the DNA major groove. We further reveal that this protein exhibits DNA-nicking activity which requires its polymeric state as well as ATP hydrolysis and through this activity it converts catenated kDNA minicircles into open form. In addition, we show that LdACT specifically binds bacterial type II topoisomerase and inhibits its decatenation activity. Together, these results strongly indicate that LdACT could play a critical role in kDNA remodeling

Delignification of miscanthus using ethylenediamine (EDA) with or without ammonia and subsequent enzymatic hydrolysis to sugars.

Pretreatment of miscanthus is essential for efficient enzymatic production of cellulosic ethanol. This study reports a possible pretreatment method for miscanthus using aqueous ethylenediamine (EDA) for 30 min at 180 °C with or without ammonia. The mass ratio of miscanthus to EDA was varied from 1:3, 1:1, and 1:0.5, keeping the mass ratio of miscanthus to liquid (EDA + Water) constant at 1:8. The ammonia-to-miscanthus ratio was 1:0.25. After pretreatment with a ratio of 1:3 miscanthus to EDA, about 75 % of the lignin was removed from the raw miscanthus with 90 % retention of cellulose and 50 % of hemicellulose in the recovered solid. Enzymatic hydrolysis of the recovered solid miscanthus gave 63 % glucose and 62 % xylose conversion after 72 h. EDA provides an effective pretreatment for miscanthus, achieving good delignification and enhanced sugar yield by enzyme hydrolysis. Results using aqueous EDA with or without ammonia are much better than those using hot water and compare favorably with those using aqueous ammonia. The delignification efficiency of EDA pretreatment is high compared to that for hot-water pretreatment and is nearly as efficient as that obtained for aqueous-ammonia pretreatment

Photochemical internalization (PCI)-mediated activation of CD8 T cells involves antigen uptake and CCR7-mediated transport by migratory dendritic cells to draining lymph nodes

Antigen cross-presentation to cytotoxic CD8+ T cells is crucial for the induction of anti-tumor and anti-viral immune responses. Recently, co-encapsulation of photosensitizers and antigens into microspheres and subsequent photochemical internalization (PCI) of antigens in antigen presenting cells has emerged as a promising new strategy for inducing antigen-specific CD8+ T cell responses in vitro and in vivo. However, the exact cellular mechanisms have hardly been investigated in vivo, i.e., which cell types take up antigen-loaded microspheres at the site of injection, or in which secondary lymphoid organ does T cell priming occur? We used spray-dried poly(lactic-co-glycolic acid) (PLGA) microspheres loaded with ovalbumin and the photosensitizer tetraphenyl chlorine disulfonate (TPCS2a) to investigate these processes in vivo. Intravital microscopy and flow cytometric analysis of the murine ear skin revealed that dendritic cells (DCs) take up PLGA microspheres in peripheral tissues. Illumination then caused photoactivation of TPCS2a and induced local tissue inflammation that enhanced CCR7-dependent migration of microsphere-containing DCs to tissue-draining lymph nodes (LNs), i.e., the site of CD8+ T cell priming. The results contribute to a better understanding of the functional mechanism of PCI-mediated vaccination and highlight the importance of an active transport of vaccine microspheres by antigen presenting cells to draining LNs. Keywords: CCR7; CD8(+) T cell priming; Dendritic cell migration; Photochemical internalization; Skin-inflammation

Structural Polymorphism in F-actin

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