Biotechnology: A new opium pipe

Narcotic drugs could soon be manufactured by yeast

Synthetic biology—the technique of moving genes from creature to creature not one at a time, but by the handful—promises much but has yet to deliver. Someone who believes it can, though, is Christina Smolke of Stanford University. And, as she and her colleagues write in Nature Chemical Biology, they think they now know one way that it might.

Opiates, such as morphine, are widely used as painkillers. Some are extracted directly from opium poppies (paler, as the picture shows, than the sort familiar in Europe and North America), which grow well in places such as Afghanistan and Turkey. Others, such as oxycodone, are chemically derived from natural poppy-molecules. Many of these drugs, though, are also used for recreational purposes—particularly diamorphine, an acetylated version of the principal poppy extract that was branded “Heroin” by its manufacturer, Bayer, in the late 19th century. Since such recreational use is generally illegal, the authorities keep a strict eye on the opium trade, and would no doubt welcome the chance to make that eye even stricter by cutting poppies out of the loop and making diamorphine and its cousins from scratch in facilities they can watch. That, plus the possibility the drugs might be produced more cheaply, has encouraged Dr Smolke to use synthetic biology to see if she can create an alternative source for opiates.

To do so, her team added three crucial poppy genes to some yeast cells. When provided with the appropriate chemical precursor, the modified yeast cranked out morphine and another opiate, codeine. And when one of the poppy genes was itself replaced by two genes from Pseudomonas putida, a soil bacterium, the yeast made oxycodone and hydrocodone too. Though this prototype yeast was not particularly efficient, some further tweaking converted it into a veritable drug factory—capable of cooking up 131mg of opioids (the equivalent of about 26 medical doses of diamorphine) per litre of culture over a four-day manufacturing cycle.

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