Molecular typesetting -- proofreading without a proofreader

June 23, 2009

Researchers at the Universities of Leeds and Bristol (UK) have developed a model of how errors are corrected whilst proteins are being built.

Ensuring that proteins are built correctly is essential to the proper functioning of our bodies, but the 'quality assurance' mechanisms that take place during this manufacturing process are not fully understood.

"Scientists have been puzzled as to how this process makes so few mistakes", says Dr Netta Cohen, Reader at the University of Leeds' School of Computing.

To create a protein, the first step involves copying the relevant gene on our DNA onto a template, called RNA. This copying process is carried out by molecular machines called RNA polymerases.

"The RNA polymerase acts like an old fashioned newsprint typesetter, constructing newsprint by assembling letters one at a time. Similarly, RNA polymerase constructs RNA by reading the DNA and adding new letters to the RNA one at a time," explains Dr Cohen.

There's no way for the RNA polymerase to ensure that the correct letter is always incorporated at the right spot. "Statistically, we would expect to see a hundred-fold more errors than we actually do, so we know that some error correction must be happening. Otherwise, many more proteins in our bodies would malfunction," says Dr Cohen.

Biological experiments have shown that the RNA polymerase slides both forwards and backwards along the RNA sequence it has created. What's more, it has miniature scissors that can then cut out the last few letters of RNA.

So how are errors corrected? Intelligent typesetters would remove the last few letters when they spot an error. The new model suggests how the backward sliding stalls when passing an error, so wrong letters can be snipped off and copying can resume.

"The mechanism we've modelled has only recently been shown to be implicated in proofreading," says Dr Cohen. "In fact, there is more than one identified mechanism for ensuring that genetic code is copied correctly. The challenge now is to find out - through a combination of experimental biology and modelling - which mechanism is dominant."
-end-


University of Leeds

Related DNA Articles from Brightsurf:

A new twist on DNA origami
A team* of scientists from ASU and Shanghai Jiao Tong University (SJTU) led by Hao Yan, ASU's Milton Glick Professor in the School of Molecular Sciences, and director of the ASU Biodesign Institute's Center for Molecular Design and Biomimetics, has just announced the creation of a new type of meta-DNA structures that will open up the fields of optoelectronics (including information storage and encryption) as well as synthetic biology.

Solving a DNA mystery
''A watched pot never boils,'' as the saying goes, but that was not the case for UC Santa Barbara researchers watching a ''pot'' of liquids formed from DNA.

Junk DNA might be really, really useful for biocomputing
When you don't understand how things work, it's not unusual to think of them as just plain old junk.

Designing DNA from scratch: Engineering the functions of micrometer-sized DNA droplets
Scientists at Tokyo Institute of Technology (Tokyo Tech) have constructed ''DNA droplets'' comprising designed DNA nanostructures.

Does DNA in the water tell us how many fish are there?
Researchers have developed a new non-invasive method to count individual fish by measuring the concentration of environmental DNA in the water, which could be applied for quantitative monitoring of aquatic ecosystems.

Zigzag DNA
How the cell organizes DNA into tightly packed chromosomes. Nature publication by Delft University of Technology and EMBL Heidelberg.

Scientists now know what DNA's chaperone looks like
Researchers have discovered the structure of the FACT protein -- a mysterious protein central to the functioning of DNA.

DNA is like everything else: it's not what you have, but how you use it
A new paradigm for reading out genetic information in DNA is described by Dr.

A new spin on DNA
For decades, researchers have chased ways to study biological machines.

From face to DNA: New method aims to improve match between DNA sample and face database
Predicting what someone's face looks like based on a DNA sample remains a hard nut to crack for science.

Read More: DNA News and DNA Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.