Adding Letters to the DNA Alphabet

semi-synthetic bacterium

Credit: William B. Kiosses

The recipes for life, going back billions of years to the earliest single-celled organisms, are encoded in a DNA alphabet of just four letters. But is four as high as the DNA code can go? Or, as researchers have long wondered, is it chemically and biologically possible to expand the DNA code by a couple of letters?

A team of NIH-funded researchers is now answering these provocative questions. The researchers recently engineered a semi-synthetic bacterium containing DNA with six letters, including two extra nucleotides [1, 2]. Now, in a report published in Nature, they’ve taken the next critical step [3]. They show that bacteria, like those in the photo, are not only capable of reliably passing on to the next generation a DNA code of six letters, they can use that expanded genetic information to produce novel proteins unlike any found in nature.

Continue reading

The Beauty of Recycling

This image looks like a fireworks display, with multiple streaks of purple turning into red, and ending with dots of green.

Novel proteasome regulation image by Sigi Benjamin-Hong, Strang Laboratory of Apoptosis and Cancer Biology.

All cells recycle. Here, we see actin filaments (red) direct unwanted (malformed, damaged, or toxic) proteins to proteasomes (green). In these barrel-shaped compartments, proteins are chopped up into their basic building blocks, called amino acids, and recycled to make new healthy proteins. Continue reading