enzymes – GOLLYGEE!

Several media outlets have been reporting on the topic of DNA transistors, which use genetic material as a type of switch inside of a cell. NPR has a pretty good description of the project and a link to a YouTube video:

Transistors are simple on/off switches. Computers are made of many millions of these switches. And to program a cell, you need a biological version. As Endy reports this week in Science, he managed to make one out of DNA.

His switch, which he calls a “transcriptor,” is a piece of DNA that he can flip on and off, using chemicals called enzymes. Endy put several of these DNA switches inside his bacteria. He could use the switches to build logic circuits that program each cell’s behavior. For example, he could tell a cell to change color in the presence of both enzyme A and enzyme B. That’s a simple program: IF enzyme A AND enzyme B [are present] THEN turn green. For an in-depth look, check out Endy’s own explanation on YouTube.

There is also the following graphical explanation:

The enzymes turn on the switch and allow the transcription of a DNA sequence into RNA. This transcription will then lead to some observable cellular phenomenon. Note that both enzymes must be present in a cell for the switch to be turned on.

The research appears in Science.

A 3D render of an enzyme

Enzymes that catalyze the most important biological reactions generally have only one function. Other enzymes can carry out multiple less important reactions. From Science News:

Of the 1,081 enzymes studied, 404 were generalists that carried out multiple chemical reactions. The 677 specialist enzymes, it turned out, were essential for the bacterium’s survival, for example tasked with turning genetic instructions into proteins.

Revealing where the generalists and specialists do their stuff in a metabolic network could help scientists identify starter enzymes for designing new drugs, fuels and other chemical products. It also may help biologists create organisms from scratch, says Pablo Carbonell, a synthetic biologist at the University of Évry-Val-d’Essonne in France.

The work clears up a long-standing question about promiscuity and monogamy among enzymes. Enzymes act on what scientists call substrates; for example amylase, an enzyme in saliva, breaks down the substrate starch. For more than 100 years enzymes have been presented as exceedingly loyal to their substrates. But the growing number of promiscuous enzymes that interact with multiple substrates and carry out multiple reactions have forced scientists to face the fact that all enzymes aren’t the dedicated, loyal players they’ve been made out to be.

GOLLYGEE!

Tag: enzymes

DNA transistors

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