How 'molecular machines' kick start gene activation revealed

November 6, 2008

How 'molecular machines' inside cells swing into action to activate genes at different times in a cell's life is revealed today in new research published in Molecular Cell.

Genes are made of double stranded DNA molecules containing the coded information an organism's cells need to produce proteins. The DNA double strands need to be 'melted out' and separated in order for the code to be accessed. Once accessed, the genetic codes are converted to messenger RNAs (mRNA) which are used to make proteins. Cells need to produce particular proteins at different times in their lives, to help them respond and adapt to changes in their environment.

The new study outlines exactly how a molecular machine called RNA polymerase, which reads the DNA code and synthesizes mRNA, is kickstarted by specialised activator proteins. The scientists have discovered that RNA polymerase uses a tightly regulated internal blocking system that prevents genes from being activated when they are not needed.

Using electron microscopy to look at the inner workings of bacterial cells, the researchers discovered that the DNA strand-separating process is kickstarted when RNA polymerase is modified by an activator protein, which the cell sends to the site of the gene that needs to be switched on.

This activator protein jump-starts the RNA polymerase machine by removing a plug which blocks the DNA's entrance to the machine. The activator protein also causes the DNA strands to shift position so that the DNA lines up with the entrance to the RNA polymerase. Once these two movements have occurred and the DNA strands are in position, the RNA polymerase machine gets to work melting them out, so that the information they contain can be processed to produce mRNA, and ultimately allow production of proteins.

Professor Xiaodong Zhang, lead author of the paper from the Department of Life Sciences at Imperial College London, explains the significance of the team's findings, saying:

"Understanding how the RNA polymerase gene transcription 'machine' is activated, and how it is stalled from working when it is not needed, gives us a better insight than ever before into the inner workings of cells, and the complex processes that occur to facilitate the carefully regulated production of proteins."

Professor Martin Buck, Head of Imperial's Division of Biology and one of the paper's co-authors, adds that understanding how this process works in bacteria cells is of particular interest, because it is this gene transcription and protein production process which allows bacterial cells to adapt, respond and thrive despite changes in their environment:

"In other words, this is the process that occurs inside bacteria that makes them so good at survival. Many bacteria cause infection and disease in humans, and are hard to defeat. Bacterial RNA polymerase is a proven target for antibiotics such as rifampicin, against which many bacteria have become resistant. Insights gained form our research will now provide opportunities and strategies for the design of novel antibacterial compounds," he concludes.

Source: Imperial College London

Explore further: Discovery of trigger for bugs' defenses could lead to new antibiotics

Related Stories

Researchers discover new mechanism of DNA repair

July 3, 2015

The DNA molecule is chemically unstable giving rise to DNA lesions of different nature. That is why DNA damage detection, signaling and repair, collectively known as the DNA damage response, are needed.

Recommended for you

At Saturn, one of these rings is not like the others

September 2, 2015

When the sun set on Saturn's rings in August 2009, scientists on NASA's Cassini mission were watching closely. It was the equinox—one of two times in the Saturnian year when the sun illuminates the planet's enormous ring ...

For 2-D boron, it's all about that base

September 2, 2015

Rice University scientists have theoretically determined that the properties of atom-thick sheets of boron depend on where those atoms land.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.