Antimicrobial activity of flavonoids

In order to extract the maximum amount of information from the rapidly accumulating genome sequences, all conserved genes need to be classified according to their homologous relationships. Comparison of proteins encoded in seven complete genomes from five major phylogenetic lineages and elucidation of consistent patterns of sequence similarities allowed the delineation of 720 clusters of orthologous groups (COGs). Each COG consists of individual orthologous proteins or orthologous sets of paralogs from at least three lineages. Orthologs typically have the same function, allowing transfer of functional information from one member to an entire COG. This relation automatically yields a number of functional predictions for poorly characterized genomes. The COGs comprise a framework for functional and evolutionary genome analysis.

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A genomic perspective on protein families

An X-ray structure of the F1 portion of the mitochondrial ATP synthase shows asymmetry and differences in nucleotide binding of the catalytic β subunits that support the binding change mechanism with an internal rotation of the γ subunit. Other structural and mutational probes of the F1 and F0 portions of the ATP synthase are reviewed, together with kinetic and other evaluations of catalytic site occupancy and behavior during hydrolysis or synthesis of ATP. Subunit function as related to proton translocation and rotational catalysis is considered. Physical demonstrations of the γ subunit rotation have been achieved. The findings have implications for other enzymatic catalyses.

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The ATP Synthase—A Splendid Molecular Machine

Phosphoenolpyruvate:carbohydrate phosphotransferase systems of bacteria.

Agents that increase the permeability of the outer membrane.

We found that cells of Vibrio parahaemolyticus possess an energy-dependent efflux system for norfloxacin. We cloned a gene for a putative norfloxacin efflux protein from the chromosomal DNA of V. parahaemolyticus by using an Escherichia coli mutant lacking the major multidrug efflux system AcrAB as the host and sequenced the gene (norM). Cells of E. coli transformed with a plasmid carrying the norM gene showed elevated energy-dependent efflux of norfloxacin. The transformants showed elevated resistance not only to norfloxacin and ciprofloxacin but also to the structurally unrelated compounds ethidium, kanamycin, and streptomycin. These results suggest that this is a multidrug efflux system. The hydropathy pattern of the deduced amino acid sequence of NorM suggested the presence of 12 transmembrane domains. The deduced primary structure of NorM showed 57% identity and 88% similarity with that of a hypothetical E. coli membrane protein, YdhE. No reported drug efflux protein in the sequence databases showed significant sequence similarity with NorM. Thus, NorM seems to be a novel type of multidrug efflux protein. We cloned the ydhE gene from E. coli. Cells of E. coli transformed with the cloned ydhE gene showed elevated resistance to norfloxacin, ciprofloxacin, acriflavine, and tetraphenylphosphonium ion, but not to ethidium, when MICs were measured. Thus, it seems that NorM and YdhE differ somehow in substrate specificity.

NorM, a Putative Multidrug Efflux Protein, of Vibrio parahaemolyticus and Its Homolog in Escherichia coli

Multidrug efflux transporters in the MATE family.

Two new genes (mexXY) similar to mexAB, mexCD, and mexEF and mediating multidrug resistance were cloned from the chromosome of Pseudomonas aeruginosa. Elevated ethidium extrusion was observed with Escherichia coli cells harboring the plasmid carrying mexXY. This MexXY system confers higher resistance to fluoroquinolones than the MexAB and MexCD systems, and E. coli TolC or P. aeruginosa OprM is necessary for the function of the MexXY system.

Expression in Escherichia coli of a new multidrug efflux pump, MexXY, from Pseudomonas aeruginosa.

https://www.jbc.org/content/277/7/5360.full.pdf

Functional cloning and characterization of a plant efflux carrier for multidrug and heavy metal detoxification

Thirteen phenolic glycosides including six new compounds were isolated from seeds of Cassia tora (Leguminosae). The structures of the new compounds, rubrofusarin triglucoside (7), nor-rubrofusarin gentiobioside (9), demethylflavasperone gentiobioside (10), torachrysone gentiobioside (11), torachrysone tetraglucoside (12) and torachrysone apioglucoside (13), were elucidated on the basis of spectroscopic and chemical evidence. The effects of the phenolic glycosides, their aglycones and several other compounds structurally related to them on Escherichia coli K12, Pseudomonas aeruginosa PAO1 and some strains of Staphylococcus aureus were then examined. Among them, torachrysone (15), toralactone (16), aloe-emodin (18), rhein (19) and emodin (20) showed noticeable antibacterial effects on four strains of methicillin-resistant Staphylococcus aureus with a minimum inhibitory concentration of 2-64 micrograms/ml. On the other hand, the phenolic compounds tested did not show strong antibacterial effects on E. coli and P. aeruginosa.

/pdf/phenolic-constituents-of-cassia-seeds-and-antibacterial-4k0cxx8kvo.pdf

Tomofusa Tsuchiya

Papers

NorM, a Putative Multidrug Efflux Protein, of Vibrio parahaemolyticus and Its Homolog in Escherichia coli

Multidrug efflux transporters in the MATE family.

Expression in Escherichia coli of a new multidrug efflux pump, MexXY, from Pseudomonas aeruginosa.

Functional cloning and characterization of a plant efflux carrier for multidrug and heavy metal detoxification

Phenolic constituents of Cassia seeds and antibacterial effect of some naphthalenes and anthraquinones on methicillin-resistant Staphylococcus aureus.