Scientists Discover the On/Off Switch of the Cell's Copy Machine


Our cells are amazing places that contain countless molecular machines all working together to perform multiple and important functions simultaneously.

Within our cells are strands of DNA, which are very long molecules containing vital information for cell maintenance and reproduction. But that information must be made accessible to the cell’s machines in order for them to perform their functions. Therefore, the molecular “motor” called RNA polymerase constantly reads and copies shorter segments, called transcripts, of the DNA for the machines to use. If a transcript is damaged and the information is still needed, more transcripts can be produced from the original DNA.

The RNA polymerase is remarkable in its efficiency, design, and effectiveness. But what if it never stopped transcribing? What if its copying went out of control, littering the cell with genetic debris? What if it transcribed the wrong genes, or was blocked from transcribing at all?

Recently, researchers at Imperial College London identified another amazing cellular machine, a kind of switch that “turns on” the RNA polymerase. Their findings appeared in the November 7th edition of the journal Molecular Cell.1 A remarkably high-resolution cryo-electron microscope was used to visualize this tiny protein switch in action. According to an Imperial College press release, “this activator protein jump-starts the RNA polymerase machine by removing a plug which blocks the DNA's entrance to the machine.”2

This control, or regulation, of the transcription is vital. It is not enough for a protein to have the ability to perform a specific function within a cell, as amazing and essential as that might be in itself. That function must be regulated. A car without the regulatory mechanisms of, at the very least, brakes and an ignition switch would be largely ineffective as a means of transportation.

This newly-discovered protein switch is no surprise to those who follow the creation model, which expects an ingenious Creator to have invented molecular machines that are not only efficient in their operations, but also in the regulation of those operations.

References

  1. Bose, D. et al. 2008. Organization of an Activator-Bound RNA Polymerase Holoenzyme. Molecular Cell. 32 (3): 337-346.
  2. How 'molecular machines' kick start gene activation revealed. Imperial College London press release, November 6, 2008.

* Mr. Thomas is Science Writer.

Article posted on November 17, 2008.