The heroics of the cell's DNA repair system are well known, but new research is adding yet another incredible facet to the story. Experimentalists tagged DNA repair proteins with nanocrystals that light up. They then observed how they interact with DNA molecules. As reported:
They watched while UvrA proteins randomly jumped from one DNA molecule to the next, holding on to one spot for about seven seconds before hopping to another site. But when UvrA formed a complex with two UvrB molecules (UvrAB), a new and more efficient search technique emerged: the complex slid along the DNA tightrope for as long as 40 seconds before detaching itself and jumping to another molecule. ... In addition to random jumping and sliding, the researchers also observed what they called "paused motion," in which UvrAB's motion seemed slower and purposeful.
Proteins certainly do perform remarkable functions. As one researcher explained:
How this system works is an important unanswered question in this field. It has to be able to identify very small mistakes in a 3-dimensional morass of gene strands. It's akin to spotting potholes on every street all over the country and getting them fixed before the next rush hour.
It would be extremely unlikely for blind variations to stumble upon such protein designs. With evolution we must believe that such proteins just happened to arise and then were selected because they helped in the DNA repair system. If you believe that then I have a bridge to sell you.
