Molecular Puzzle of Mitosis Pieces Solved

I’ve always been amazed at the complexity of biological processes at a microscopic level. Countless chemicals, enzymes, proteins and the like dance an intricate tango in order to keep this thing we call life moving forward billions of times every day. One of these processes that fascinated me during high school was cell division.

A graphic rendering of the molecular strings that is a protein (colored) interacting with DNA (grey).

If you think about it for a minute, the ability for multiple proteins and enzymes to work together in a very specific way in order to split chromosomes, move them apart and create new nuclear envelopes around them forming two new cells is astounding. While we may have figured out the basic molecules and processes involved, much of how it all goes down on the smallest of levels remains a mystery.

But it’s a mystery that we’re beginning to solve.

In a recent study published in Nature, scientists from Penn State’s Center for Eukaryotic Gene Regulation have successfully imaged the interaction of an enzyme crucial to mitosis and the genetic material it manipulates.

The magnified substance is known as RCC1; a protein responsible for binding newly separated DNA into tightly packed chromosomes and transporting the daughter nucleus away from the original. Understanding how this protein recognizes and interacts with the chromosomes is an important step because the same processes allow DNA to be “read” by the engines of life even while tightly compacted. It gives a glimpse into how healthy cells operate on the most basic levels.

So if it’s so important, why hasn’t anybody done it before now, you ask? Well, because it wasn’t possible. In fact, the research team involved spent the better part of a decade developing the methods that allowed them to make this breakthrough. We’re talking about creating a 3-D image of molecules at the atomic level, i.e., almost small enough to map where individual atoms are located. To achieve this amazing feat, the team headed to the Advanced Photon Source at Argonne National Laboratory.

A full view of the rendered protein interacting with nucleotides.

This facility creates x-rays synchronized together into a laser beam with wavelengths just tenths of a nanometer long. But first, in order to be able to use these x-rays to image RCC1, the scientists first had to grow molecular crystals of the protein while bound to the genetic material. The rigid structure freezes the action in place so that the x-rays can bounce off of a stable target. Once in place, the x-rays smashed into the sample, completely obliterating it. However, the waves came in so quickly that enough of them bounced off of the sample to create an image of it before it was destroyed.

The machines that make this sort of research possible are truly amazing and I highly recommend visiting a facility nearby if you ever get the chance. Besides Argonne, which is outside of Chicago, other advanced light sources are located at the Stanford Linear Accelerator Center in Palo Alto, California and Oak Ridge National Laboratory in Tennessee.

Though several of these types of machines exist in this country alone and have for some time now, techniques to prepare samples in order to make full use of their abilities are constantly being improved. Now that the team has successfully completed the process once, it should open the door to study the fundamental interactions of many more biological agents and the genetic material they shape. In the end, this line of research should greatly enhance our knowledge of the most basic functions of life, allowing us to recognize – and in the end, prevent – things going wrong.

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About bigkingken

A science writer dedicated to proving that the Big Ten - or the Committee on Institutional Cooperation, if you will - is more than athletics.
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