The multiple antibiotic resistance (mar) operon of Escherichia coli is a paradigm for chromosomally encoded antibiotic resistance in enteric bacteria. The locus is recognised for its ability to modulate efflux pump and porin expression via two encoded transcription factors, MarR and MarA. Here we map binding of these regulators across the E. coli genome and identify an extensive mar regulon. Most notably, MarA activates expression of genes required for DNA repair and lipid trafficking. Consequently, the mar locus reduces quinolone-induced DNA damage and the ability of tetracyclines to traverse the outer membrane. These previously unrecognised mar pathways reside within a core regulon, shared by most enteric bacteria. Hence, we provide a framework for understanding multidrug resistance, mediated by analogous systems, across the Enterobacteriaceae. Transcription factors MarR and MarA confer multidrug resistance in enteric bacteria by modulating efflux pump and porin expression. Here, Sharma et al. show that MarA also upregulates genes required for lipid trafficking and DNA repair, thus reducing antibiotic entry and quinolone-induced DNA damage.

Background: Delivery of the vesicle into the pre-fusion state during tethering is not understood. Results: Interactions between the COG complex, golgins and Rabs were mapped. Two ends of the golgin TMF both bind COG and different Rabs, the middle binds the target membrane. Conclusion: COG may reel the vesicle into docking along the golgin. Significance: Mechanistic link between tethering complex and coiled tether established.

Bacterial multidrug efflux systems are a major mechanism of antimicrobial resistance and are fundamental to the physiology of Gram-negative bacteria. The resistance-nodulation-division (RND) family of efflux pumps is the most clinically significant, as it is associated with multidrug resistance. Expression of efflux systems is subject to multiple levels of regulation, involving local and global transcriptional regulation as well as post-transcriptional and post-translational regulation. The best-characterised RND system is AcrAB-TolC, which is present in Enterobacteriaceae. This review describes the current knowledge and new data about the regulation of the acrAB and tolC genes in Escherichia coli and Salmonella enterica.

Enterotoxigenic Escherichia coli (ETEC) cause severe diarrhoea in humans and neonatal farm animals. Annually, 380,000 human deaths, and multi-million dollar losses in the farming industry, can be attributed to ETEC infections. Illness results from the action of enterotoxins, which disrupt signalling pathways that manage water and electrolyte homeostasis in the mammalian gut. The resulting fluid loss is treated by oral rehydration. Hence, aqueous solutions of glucose and salt are ingested by the patient. Given the central role of enterotoxins in disease, we have characterised the regulatory trigger that controls toxin production. We show that, at the molecular level, the trigger is comprised of two gene regulatory proteins, CRP and H-NS. Strikingly, this renders toxin expression sensitive to both conditions encountered on host cell attachment and the components of oral rehydration therapy. For example, enterotoxin expression is induced by salt in an H-NS dependent manner. Furthermore, depending on the toxin gene, expression is activated or repressed by glucose. The precise sensitivity of the regulatory trigger to glucose differs because of variations in the regulatory setup for each toxin encoding gene.

Our data indicate that metformin may play a pivotal role in modulating the anti-oxidant system, including the SOD machinery, in breast cancer-derived cells. Our observations were validated by in silico analyses, indicating a close interaction between SOD and metformin. We also found that metformin may inhibit breast cancer-derived cell proliferation through apoptosis induction via the mitochondrial pathway. Finally, we found that metformin may modulate the pro-apoptotic Bax, anti-apoptotic Bcl-2, MMP-2, MMP-9, miR-21 and miR-155 expression levels. These findings may be instrumental for the clinical management and/or (targeted) treatment of breast cancer.

SummaryThe Escherichia coli marRAB operon is a paradigm for chromosomally encoded antibiotic resistance. The operon exerts its effect via an encoded transcription factor called MarA that modulates efflux pump and porin expression. In this work, we show that MarA is also a regulator of biofilm formation. Control is mediated by binding of MarA to the intergenic region upstream of the ycgZ‐ymgABC operon. The operon, known to influence the formation of curli fibres and colanic acid, is usually expressed during periods of starvation. Hence, the ycgZ‐ymgABC promoter is recognised by σ38 (RpoS)‐associated RNA polymerase (RNAP). Surprisingly, MarA does not influence σ38‐dependent transcription. Instead, MarA drives transcription by the housekeeping σ70‐associated RNAP. The effects of MarA on ycgZ‐ymgABC expression are coupled with biofilm formation by the rcsCDB phosphorelay system, with YcgZ, YmgA and YmgB forming a complex that directly interacts with the histidine kinase domain of RcsC.

A Basidiomycetes fungus belonging to polypore family of mushrooms, Ganoderma lucidum (GL), has been known since a long time for their myriad therapeutic indications. Renowned as an invaluable resource of cardinal mycoconstituents they encompass numerous terpenoids polysaccharides and proteins. Possessing the therapeutically potent lanosteroidal skeleton, terpenoids are upheld for their invariable participation in therapeutically diverse bioactivities. Polysaccharides and proteins exhibiting distinguishable bioactivities provide this oriental mushroom with additional edges over immune function and anti-cancer potential. This review is a concerted effort to throw light upon the therapeutic versatility of the fungus, shadowed by various other natural products. An effort has been made towards conglomerating the mycoconstituents decisive for the many activities portrayed by this fungus. More importantly, this review seeks to fathom the inextricable role played by derivatives in modulating signaling cascades such as downregulation of various mitogenic pathways, inhibiting growth factors, or upregulating certain pathways enhancing cellular integrity.

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