Transporters are a relatively undervalued set of proteins contributing to the control of biotechnological fluxes.
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We highlight the evidence for this.
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This is true for both ‘influx’ and ‘efflux’ transporters.
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Transporter engineering offers many opportunities to overcome flux control.
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The methods of synthetic biology offer particular promise for transporter engineering.
Because they mainly do not involve chemical changes, membrane transporters have been a Cinderella subject in the biotechnology of small molecule production, but this is a serious oversight. Influx transporters contribute significantly to the flux towards product, and efflux transporters ensure the accumulation of product in the much greater extracellular space of fermentors. Programmes for improving biotechnological processes might therefore give greater consideration to transporters than may have been commonplace. Strategies for identifying important transporters include expression profiling, genome-wide knockout studies, stress-based selection, and the use of inhibitors. In addition, modern methods of directed evolution and synthetic biology, especially those effecting changes in energy coupling, offer huge opportunities for increasing the flux towards extracellular product formation by transporter engineering.
