Extrusion of drugs or drug-like compounds through bacterial efflux pumps is a serious health issue that leads to loss in drug efficacy. Combinatorial therapies of low-efficacy drugs with efflux pump inhibitors may help to restore the activities of such drugs. In this quest, natural products are attractive molecules, since in addition to their wide range of bioactivities they may inhibit efflux pumps. The current work repurposed the bioactive alkaloid roemerine as a potential efflux pump inhibitor. In Bacillus subtilis, both Bmr and BmrA, belonging to the major facilitator and the ATP-binding cassette superfamilies, respectively, were found to be inhibited by roemerine. Scanning electron microscopy and RNA-Seq analyses showed that it potentiated the effect of berberine. Growth rates and checkerboard assays confirmed the synergy of roemerine and berberine and that roemerine prevented berberine efflux by inhibiting Bmr. Transport assays with inverted membrane vesicles prepared from Escherichia coli overexpressing BmrA showed that increasing roemerine concentration decreased the transport of doxorubicin, the BmrA substrate, confirming that roemerine may also be considered as an inhibitor of BmrA. Thus, these findings suggest that conjugation of roemerine to substrates of efflux pumps, Bmr and BmrA, may help to potentiate the activity of their drug substrates.
An increase in the number of elderly people suffering from the symptoms of Parkinson's disease is leading to an expansion in the market size of 3,4-dihydroxyphenyl-l-alanine (l-DOPA), which is the most commonly used drug for the treatment of this disease. Need for better quality products through economically feasible and sustainable processes makes biotechnological approaches attractive. The current study is focused on heterologous expression of Ralstonia solanacearum tyrosinase in Corynebacterium glutamicum cells to produce l-DOPA during growth on glucose or glucose/xylose mixtures. Whole-cells pre-grown on glucose were further exploited for biotransformation of l-tyrosine to l-DOPA. To prevent l-DOPA oxidation, not only the most commonly used agent, ascorbic acid, but also for the first time, thymol was evaluated. The highest l-DOPA titer was 0.26 ± 0.02 g/L at the end of growth on a mixture of 1% xylose and 3% glucose in the presence of 200 μM thymol as the oxidation inhibitor. The ability to co-utilize glucose and xylose to reach this titer could make these cells ideal for l-DOPA production using hydrolyzed lignocellulosic biomass. When the pre-grown cells were further used for biotransformation, the highest l-DOPA yield was 0.61 ± 0.02 g/gDCW with 4 mM ascorbic acid. Since l-tyrosine biotransformation is primarily dependent on tyrosinase activity, yield in this route could be improved by optimizing reaction conditions. As the industrial workhorse for amino acid production, these C. glutamicum cells will clearly benefit from strain development efforts and bioprocess optimization towards sustainable and economically feasible l-DOPA production. Key points• Fermentative l-DOPA production was achieved in C. glutamicum.• Tyrosinase produced by C. glutamicum cells successfully transformed l-Tyr.• Thymol proved to be a significant oxidation inhibitor for l-DOPA production.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.