Structural characterization and surface activities of biogenic rhamnolipid surfactants from Pseudomonas aeruginosa isolate MN1 and synergistic effects against methicillin-resistant Staphylococcus aureus

The aim of present work was to study chemical structures and biological activities of rhamnolipid biosurfactants produced by Pseudomonas aeruginosa MN1 isolated from oil-contaminated soil. The results of liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis revealed that total rhamnolipids (RLs) contained 16 rhamnolipid homologues. Di-lipid RLs containing C₁₀-C₁₀ moieties were by far the most predominant congeners among mono-rhamnose (53.29?%) and di-rhamnose (23.52?%) homologues. Mono-rhamnolipids form 68.35?% of the total congeners in the RLs. Two major fractions were revealed in the thin layer chromatogram of produced RLs which were then purified by column chromatography. The retardation factors (R _f) of the two rhamnolipid purple spots were 0.71 for RL1 and 0.46 for RL2. LC-MS/MS analysis proved that RL1 was composed of mono-RLs and RL2 consisted of di-RLs. RL1 was more surface-active with the critical micelle concentration (CMC) value of 15?mg/L and the surface tension of 25 mN/m at CMC. The results of biological assay showed that RL1 is a more potent antibacterial agent than RL2. All methicillin-resistant Staphylococcus aureus (MRSA) strains were inhibited by RLs that were independent of their antibiotic susceptibility patterns. RLs remarkably enhanced the activity of oxacillin against MRSA strains and lowered the minimum inhibitory concentrations of oxacillin to the range of 3.12?C6.25???g/mL.     

SHOC2 and CRAF Mediate ERK1/2 Reactivation in Mutant NRAS-mediated Resistance to RAF Inhibitor

ERK1/2 signaling is frequently dysregulated in tumors through BRAF mutation. Targeting mutant BRAF with vemurafenib frequently elicits therapeutic responses; however, durable effects are often limited by ERK1/2 pathway reactivation via poorly defined mechanisms. We generated mutant BRAF^V600E melanoma cells that exhibit resistance to PLX4720, the tool compound for vemurafenib, that co-expressed mutant (Q61K) NRAS. In these BRAF^V600E/NRAS^Q61K co-expressing cells, re-activation of the ERK1/2 pathway during PLX4720 treatment was dependent on NRAS. Expression of mutant NRAS in parental BRAF^V600 cells was sufficient to by-pass PLX4720 effects on ERK1/2 signaling, entry into S phase and susceptibility to apoptosis in a manner dependent on the RAF binding site in NRAS. ERK1/2 activation in BRAF^V600E/NRAS^Q61K cells required CRAF only in the presence of PLX4720, indicating a switch in RAF isoform requirement. Both ERK1/2 activation and resistance to apoptosis of BRAF^V600E/NRAS^Q61K cells in the presence of PLX4720 was modulated by SHOC-2/Sur-8 expression, a RAS-RAF scaffold protein. These data show that NRAS mutations confer resistance to RAF inhibitors in mutant BRAF cells and alter RAF isoform and scaffold molecule requirements to re-activate the ERK1/2 pathway.     

Effects of Synbiotics and Probiotics Supplementation on Serum Levels of Endotoxin,Heat Shock Protein 70 Antibodies and Inflammatory Markers in Hemodialysis Patients: a Randomized Double-Blinded Controlled Trial

Probiotics and Antimicrobial Proteins - The aim of this study was to investigate the effects of probiotic and synbiotic supplementation on serum inflammatory markers, endotoxin, and anti-HSP70 in...     

The secretome of mesenchymal stem cells and oxidative stress: challenges and opportunities in cell-free regenerative medicine

Molecular Biology Reports - Over the last decade, mesenchymal stem cells (MSCs) have been considered a suitable source for cell-based therapy, especially in regenerative medicine. First, the...     

Mobile DNA distributions refine the phylogeny of “matsutake” mushrooms, Tricholoma sect. Caligata

“Matsutake” mushrooms are formed by several species of Tricholoma sect. Caligata distributed across the northern hemisphere. A phylogenetic analysis of matsutake based on virtually neutral mutations in DNA sequences resolved robust relationships among Tricholoma anatolicum, Tricholoma bakamatsutake, Tricholoma magnivelare, Tricholoma matsutake, and Tricholoma sp. from Mexico (=Tricholoma sp. Mex). However, relationships among these matsutake and other species, such as Tricholoma caligatum and Tricholoma fulvocastaneum, were ambiguous. We, therefore, analyzed genomic copy numbers of σ _marY1 , marY1, and marY2N retrotransposons by comparing them with the single-copy mobile DNA megB1 using real-time polymerase chain reaction (PCR) to clarify matsutake phylogeny. We also examined types of megB1-associated domains, composed of a number of poly (A) and poly (T) reminiscent of RNA-derived DNA elements among these species. Both datasets resolved two distinct groups, one composed of T. bakamatsutake, T. fulvocastaneum, and T. caligatum that could have diverged earlier and the other comprising T. magnivelare, Tricholoma sp. Mex, T. anatolicum, and T. matsutake that could have evolved later. In the first group, T. caligatum was the closest to the second group, followed by T. fulvocastaneum and T. bakamatsutake. Within the second group, T. magnivelare was clearly differentiated from the other species. The data suggest that matsutake underwent substantial evolution between the first group, mostly composed of Fagaceae symbionts, and the second group, comprised only of Pinaceae symbionts, but diverged little within each groups. Mobile DNA markers could be useful in resolving difficult phylogenies due to, for example, closely spaced speciation events.     

Structure of the Rtt109-AcCoA/Vps75 complex and implications for chaperone-mediated histone acetylation

Yeast Rtt109 promotes nucleosome assembly and genome stability by acetylating K9, K27, and K56 of histone H3 through interaction with either of two distinct histone chaperones, Vps75 or Asf1. We report the crystal structure of an Rtt109-AcCoA/Vps75 complex revealing an elongated Vps75 homodimer bound to two globular Rtt109 molecules to form a symmetrical holoenzyme with a ～12?? diameter central hole. Vps75 and Rtt109 residues that mediate complex formation in the crystals are also important for Rtt109-Vps75 interaction and H3K9/K27 acetylation both in?vitro and in yeast cells. The same Rtt109 residues do not participate in Asf1-mediated Rtt109 acetylation in?vitro or H3K56 acetylation in yeast cells, demonstrating that Asf1 and Vps75 dictate Rtt109 substrate specificity through distinct mechanisms. These studies also suggest that Vps75 binding stimulates Rtt109 catalytic activity by appropriately presenting the H3-H4 substrate within the central cavity of the holoenzyme to promote H3K9/K27 acetylation of new histones before deposition.     

Evaluation of Physicochemical Activity of Anticancer Fusion Proteins; Enterocin A- R type pyocin-Lactocin-Ligand Against Gastric Cancer Cell Line by Real-Time RT PCR Technique

International Journal of Peptide Research and Therapeutics - Gastric cancer treatment remains a major challenge. There are many reports on the positive efficacy of Bacteriocins associated with...