Hacking the Cell's Circuitry

By Christine Gorman

Biologists have spent much of the past century taking cells apart to figure out what makes them tick. Adam Arkin, 33, a physical chemist who divides his time between the University of California, Berkeley, and the Lawrence Berkeley National Lab, wants to put the pieces back together again. His goal is to create a computer model of how the cell works so that someday he'll be able to design his own cells from scratch.

It's a daunting task. A single enzyme in a liver cell may be controlled by as many as 14 different regulatory processes. Multiply that by thousands of interconnected chemical reactions operating simultaneously in billions of cells, and you've got one incredibly complex system. But Arkin knows that computer-chip designers manage similar levels of complexity. "Good engineers in the 1960s could probably understand all the circuitry that people had built," Arkin says. "But when integrated circuits were developed, that became impossible." There were just too many pieces to put together.

Enter a computer program called SPICE (simulation program for integrated circuit evaluation), which was developed at the University of California, Berkeley, in the 1970s. SPICE allowed engineers to analyze their electronic circuits and predict, more or less accurately, how they would work before they were built. There would always be bugs to iron out, but at least the program pointed chip designers in the right direction.

Arkin is developing a similar program he calls bio/SPICE that he hopes will do for the cell what SPICE did for the chip. His first targets are simple bacteria. "They're still complicated enough that we get depressed," Arkin admits with a laugh. But he has already had some success grouping reactions together by the kinds of jobs they do. And, sure enough, some of them bear a remarkable resemblance to the gates and switches of an electronic circuit.

Of course, no one knows for sure whether Arkin or anyone else will be able to develop a working computer model of the cell. But it's the sort of project that could keep scientists busy for another 100 years.

--By Christine Gorman