DYNAMIC BEHAVIOR OF METHYLENE BLUE ON E. coli K30 CAPSULAR POLYSACCHARIDE USING LAYER BY LAYER SELF-ASSEMBLY TECHNIQUE

Layer-by-layer (LbL) self-assembly is one of the unique methods for fabrication of ultra-thin film. This technique has immense application aross many fields in today’s life. In this paper, we have presented the fabrication of the thin film comprising of antifungal and antibacterial cationic dye methylene blue with negatively charged E. coli K30 bacterial polysaccharide sharing with PAH. The multilayers were characterized by UV–Vis absorption spectra and AFM. Various photophysical behaviors were investigated. Such studies provide a new light in the research of layer by layer self-assembly technique.

PelX is a UDP-N-acetylglucosamine C4-epimerase involved in Pel polysaccharide–dependent biofilm formation

Pel is a GalNAc-rich bacterial polysaccharide that contributes to the structure and function of Pseudomonas aeruginosa biofilms. The pelABCDEFG operon is highly conserved among diverse bacterial species, and Pel may therefore be a widespread biofilm determinant. Previous annotation of pel gene clusters has helped us identify an additional gene, pelX, that is present adjacent to pelABCDEFG in >100 different bacterial species. The pelX gene is predicted to encode a member of the short-chain dehydrogenase/reductase (SDR) superfamily, but its potential role in Pel-dependent biofilm formation is unknown. Herein, we have used Pseudomonas protegens Pf-5 as a model to elucidate PelX function as Pseudomonas aeruginosa lacks a pelX homologue in its pel gene cluster. We found that P. protegens forms Pel-dependent biofilms; however, despite expression of pelX under these conditions, biofilm formation was unaffected in a ΔpelX strain. This observation led us to identify a pelX paralogue, PFL_5533, which we designate here PgnE, that appears to be functionally redundant to pelX. In line with this, a ΔpelX ΔpgnE double mutant was substantially impaired in its ability to form Pel-dependent biofilms. To understand the molecular basis for this observation, we determined the structure of PelX to 2.1 Å resolution. The structure revealed that PelX resembles UDP-GlcNAc C4-epimerases. Using 1H NMR analysis, we show that PelX catalyzes the epimerization between UDP-GlcNAc and UDP-GalNAc. Our results indicate that Pel-dependent biofilm formation requires a UDP-GlcNAc C4-epimerase that generates the UDP-GalNAc precursors required by the Pel synthase machinery for polymer production.

Marine Bacterial Polysaccharide EPS11 Inhibits Cancer Cell Growth and Metastasis via Blocking Cell Adhesion and Attenuating Filiform Structure Formation

Our previous results suggested that EPS11, a novel marine bacterial polysaccharide, might be a potential drug candidate for human non-small cell lung carcinoma treatment. In this study, we further investigate the anticancer mechanisms against liver cancer and the anti-metastatic effects in vivo of EPS11. Firstly, we found that EPS11 exerts cytotoxic effects via blocking cell adhesion and destroying filiform structure formation in Huh7.5 cells. Moreover, mass spectrometry-based proteomic analysis of EPS11-treated Huh7.5 cells revealed that expression of many adhesion-related proteins was significantly changed. It is noteworthy that the expression of CD99, a key factor related to cell adhesion, migration and cell death, is remarkably down-regulated after EPS11 treatment. Importantly, over-expression of CD99 partly rescues cell death rate, and improves cell adhesion and migration ability in Huh7.5 treated by EPS11. Thus, we propose that CD99 is a potential action target of EPS11, inhibiting cancer cell proliferation, adhesion and migration. Notably, administration of EPS11 simultaneously with tumor induction evidently reduces tumor nodule formation in the lungs, which strongly indicates that EPS11 has anti-metastatic effects in vivo. Taken together, our results suggest that EPS11 inhibits liver cancer cell growth via blocking cell adhesion and attenuating filiform structure formation, and has potential as an anti-cancer drug, targeting metastasis of cancer cells, in the future.

Negative immunomodulation by parasitic infections in the human response to vaccines

Parasitic infections are an important cause of global morbidity and mortality and are highly prevalent in "underdeveloped" countries. The presence of parasitic infections is associated with modulation of the immune system and changes in the response to bacterial and viral vaccines. The objective of this review was to compile, summarize and analyze information about immunomodulation by parasitic infections and its effects on the immune response to vaccines. We also identified the parasites most associated with immunomodulation of vaccine responses and those vaccines most affected. In addition, articles evaluating the effect of chemoprophylaxis for malaria on the immune response against vaccines were considered. The most affected vaccines are Bacillus Calmette-Guérin and bacterial polysaccharide vaccines. Malaria is the infection most associated with decreased response to vaccines; however, there are discordant results. Chemoprophylaxis for malaria did not change the immune response to vaccination. While parasitic infections can alter the immune response to vaccination, it is important to clarify the discrepancies and establish the mechanisms.