17 October 2008

‘RNA computer’ creates zombie cells

Cosmos Online
Scientists have succeeded in programming complex instructions into strings of synthetic RNA molecules and inserting them into living cells to do their bidding.

Gene power: An artist's rendering of a complex RNA (ribonucleic acid) molecule. RNA has a broad range of functions within a cell. Credit: Nicolle Rager Fuller/U.S. National Science Foundation

SYDNEY: Scientists have succeeded in programming complex instructions into strings of synthetic RNA molecules and inserting them into living cells to do their bidding.

In a study published today in the U.S. journal Science, Maung Nyan Win and Christina Smolke – chemical engineers at the California Institute of Technology in Pasadena, U.S. – demonstrate that it is possible to program these ‘RNA computers’ to guide a cell’s behaviour.

Genetic programming

RNA, a nucleic acid similar to DNA, is an important carrier of genetic information from gene to protein. It has various functions in the cell including a vital role in protein synthesis. The RNA computer, designed by Win and Smolke, is composed of a number of individual RNA components which encode basic functions that combine to create more complex activities.

Similar to RNA computers, the first DNA computers were created in the 1990s and are able to carry out simple calculations.

Up until now, though, only individual RNA components have been used to control basic cellular processes, such as sensing molecules. But the combination of these basic components into RNA computers has now allowed Win and Smolke to control more complex functions.

The researchers said that these RNA computers operate similar to many electrical devices. They can operate as sensors, actuators (signal processors that create motion) and information processors within a living biological cell. When combined in a ‘circuit’ they can be used, in a “plug-and-play capacity” to control a variety of functions within the cell.

Logic gates

The computer can operate independently of the cell’s own machinery and can be controlled by stimuli from inside or outside the cell.

For the study, Smolke told Cosmos Online that they used the devices to encode different functions such as logic gates. As in conventional electronics, logic gates process signals. They can receive a signal and change it to produce a different output signal. The scientists were able to test the function by inserting a known signal molecule, and measuring the processed output molecule.

The structure of the RNA computers was predicted with the help of a conventional PC, a method that Adam Arkin, a bioengineer from The University of California, Berkeley, said heralds a whole new field of biotechnology.

“I wouldn’t be surprised if RNA-based gene expression engineering becomes the first cellular bioengineering field to look like other engineering fields with a computer aided design and manufacture system in place,” said Arkin, who was not involved in the study.

This new RNA computer is exciting, Arkin said, because it could work in almost any organism and doesn’t rely on other chemical factors within the cell, which is rare for this kind of genetic technology.

Biotechnology century

“These circuits could control the synthesis of commodity chemical or pharmaceuticals or could even aid microbes in fixing nitrogen for plants or acting as therapy for humans,” he added.

Farren Isaacs, a geneticist at Harvard Medical School, in Cambridge, Massachusetts, said that the study is further evidence that we are sitting at the cusp of the “biotechnology century.”

Commenting on the implications of the technology, he said: “we are confronting a different, and potentially more exciting, set of revolutions that should address some of the challenges crippling our global environment, economies, public health and political unrest rooted in advances in biotechnology.”


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