The opium poppy may soon meet his first game. Researchers in the US and Canada report today they are closing in on a long-standing goal of engineering a complex set of genes in yeast that allow microbes to synthesize morphine, codeine and other drugs that have been harvested from the poppy since before recorded history began. The new work offers the prospect of being able to produce cheaply and easily widely used drugs with new features and fewer side effects. At the same time, political experts fear that new yeast strains could allow drug traffickers to convert sugar to morphine or heroin as easily as beer lovers create homebrew today.
"It really is the potential for screwing things," said Kenneth Oye, an expert from the biotechnology policy of the Massachusetts Institute of Technology in Cambridge. "If you get the built route for the synthesis of glucose pot to morphine, it's not controllable if it comes out. You better damn well get over it before it happens," said Oye which offers several ideas to increase surveillance of new biotechnology in a commentary published online today in Nature .
Morphine, heroin and other opiate poppy products are already causing a lot of havoc. Some 16 million people worldwide use illicit drugs. In the United States alone, nearly 14,000 people died from an overdose of heroin and other opioid analgesics between 2010 and 2012, according to data compiled from 28 states by the US Centers for Disease Control and prevention. Oye said the problem is that these numbers could skyrocket if the dealers and users can brew their own medicines.
Opiates are a class of compounds called alkaloids benzylisoquinoline (CADS), which together with the related families of molecules contains about 2,500 known compounds. In addition to morphine, these include thebaine, a precursor of the analgesic oxycodone and hydrocodone, and compounds commonly used antispasmodics, antibiotics and anticancer agents. BIA are multiringed complex structures that are difficult and expensive to synthesize in a laboratory. medicinal chemists have long sought a way easier and cheaper to prepare these compounds, in the hope that they might find new drugs. Health professionals have also sought versions that have fewer side effects, such as the risk of breathing and suppressed addiction that come with morphine. But until now, the engineering of opium poppy to produce new compounds proved difficult.
"Plants have slow growth cycles, so it is difficult to fully explore all possible chemicals that can be made from the BIA way," said William DeLoache, a bioengineering doctoral student the University of California, Berkeley, and lead author of the new work on the engineering yeast. "Moving the BIA way to microbes significantly reduces the cost of drug discovery. We can handle and adjust the yeast DNA and quickly test the results. "
a long way
efforts to insert the BIA way in yeast are ongoing for the better part of a decade . But it is a major challenge, said Vincent Martin, a microbiologist at Concordia University in Montreal, Canada, whose lab has worked on the project since 09. yeast engineered to produce morphine, Martin notes, requires the addition of genes to produce enzymes that carry a chain 15 distinct chemical transformations. However, one of the greatest successes of synthetic biology to-date synthesis of yeast antimalarial drug artemisinin necessary to give the genes perform only five chemical steps.
In reengineering yeast to SDAC, researchers generally divide the project into two parts. In the first part, the researchers splicing genes for enzymes that convert the amino acid tyrosine into an intermediate compound called S-reticulin; This step creates a key branch point that can lead to the synthesis of many different compounds BIA. A path leads to the morphine and codeine, while others lead to antibiotics and anticancer compounds. To create morphine, S-reticulin is first converted in a very closely related compound called R-reticulin, which is then converted in thebaine and ultimately to morphine.
Last year, researchers led by Christina Smolke, a synthetic biologist at Stanford University in Palo Alto, California, said they gave the yeast enzymes necessary for the implementation of thebaine to morphine steps at the end of the second part of the way. And last month, Martin and colleagues reported in PLOS ONE they had designed the yeast to complete all stages of the second half moving from R-reticulin morphine.
Meanwhile, the first part of the track was more difficult to remove in yeast. Tyrosine from glucose is easy: Yeast do this naturally. In 2011, Japanese researchers reported that they have obtained the first complete half way to work in Escherichia coli bacteria, transforming tyrosine S-reticulin. But so far that has established steps did not work well in yeast. The biggest obstacle was the first step: the conversion of tyrosine to a compound called L-Dopa. When the gene that directs this step is designed in yeast, bacterial enzyme works poorly at best, said Pamela Peralta-Yahya, a synthetic biologist at the Georgia Institute of Technology in Atlanta.
But John Dueber, a bioengineer at Berkeley; DeLoache; and colleagues took a break while working on a separate project to see if L-Dopa was present in some cells. The found that an enzyme called DOPA dioxygenase, converted into L-Dopa yellowish pigment. They quickly realized that they could use this enzyme as a color sensor for detecting whether another enzyme is capable of converting tyrosine to L-Dopa.
an enzyme in yeast allows researchers to see which microbes are L-Dopa (yellow), a key step in the path to opiates. William DeLoache at UC Berkeley 
Then they teamed up with Martin and his colleagues Concordia. The group tested an enzyme from sugar beet called tyrosine hydroxylase. This beet enzyme is able to convert tyrosine to L-dopa in yeast, in the process turning the yellow Petri dish (see picture above), reports the team today Nature Chemical Biology . They were able to increase the production of L-Dopa nearly three times random mutation versions of the enzyme biosensor and using them to track those who have worked the best.
"It is nice work," said Smolke. For now, she added, the bacteria still produce higher yields of L-Dopa as yeast. "But he is preparing the ground to be able to integrate these channels in an organization," says Smolke.
For now, the stage is missing is being able to convert S-reticulin in R-reticulin, which connects the first and second halves of the full path. But apparently that's handy too. researchers at the University of Calgary have posted a summary of an online doctoral dissertation says that they have identified a plant enzyme that performs this S to R conversion, although the work has not been published yet. once it is, researchers will be able to insert the gene into yeast, filling the full path of morphine glucose. "I think it's doable in 2-3 years," said Dueber. "This area is moving much faster than we thought."
social and legal concerns
Given this speed, there is a year Dueber and Martin handed Oye, wondering if he would be willing to explore ideas how the scientific community can prevent Engineered yeast exacerbate the illegal drug trade. In their Nature comment, Oye and colleagues several recommendations. First, they suggest that businesses now that synthesize and distribute long stretches of DNA should consider carefully review applications for genes that code for key components drugmaking and block suspicious requests. These companies already undertake a process similar to the sequences of genes in microbes that could be used as biological weapons, and to report voluntarily requests of these genes to law enforcement agencies.
Other possible measures would compel researchers to design morphine producing yeast strains so they also produce unwanted toxins by homebrewers, or insert watermarks in genetic strains to make them more easy to follow if the strains fall into the hands of foreigners.
Although such measures may help deter criminals toxinmaking any watermarking or genes could also be removed by a trained and qualified microbiologist, Martin notes. Another option to slow the spread of the technology would be to request that newspapers do not provide all the genetic information of all organisms that can complement the complete transformation. (Dueber and Martin say that he has not received any request to omit data.)
At the end, a new technology for morphine production could have a profound impact on agencies Law application. But for now, agencies such as the FBI "did not recommend specific regulatory measures," said Edward You, supervisory special agent of the FBI biological weapons Countermeasures Unit of Mass Destruction Directorate in Washington, DC But he said the FBI is already part of an interagency working group, which includes representatives of the national Institutes of health and other research funding agencies, contemplating ways to keep the yeast strands modified on hands illicit drug manufacturers. And an ongoing commitment with scientists and policy analysts "will certainly facilitate these discussions," You said. "There is a window of opportunity here to negotiate security issues."
regulation play?
Yet some researchers fear that the hype around homebrewed heroin fears could cause harmful regulatory response. "I believe a thoughtful discussion of the risks, opportunities and regulatory requirements is important with this technology," says Smolke. However, she said she believes the comment Oye, for one, was "inflammatory." The new technology could in the long term, improvements on existing drugs trade led poppy and all the social ills it brings, she and others noted. laboratory-derived drugs, for example, might be easier for countries to regulate and reduce environmental damage, social unrest and violence associated with drugs derived from plants.
Smolke also notes that researchers are still a considerable distance to put together the complete chain of chemical transformations necessary for the yeast to make morphine. And if and when that happens, organizations will still be only infinitesimally small amounts of drugs. "In fact, it is more likely that a person can have easier access to morphine by dumping a lot of poppy seeds in their homebrew (or tea)," she said.
The question is how long this remains the case?
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