Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Direction Selection

30.08.2012
New method for template-directed DNA synthesis in the 3’ and 5’ directions

When a cell divides, it passes on genetic information by producing copies of its DNA. Chemists have also learned to copy DNA. In the journal Angewandte Chemie, a German team has now introduced a new copying technique that uses a single strand of DNA as the “master copy”, like a cell, but does not require enzymes. Unlike earlier methods, it allows for stepwise growth of the chain in both the direction preferred by nature and the opposite direction typical of current DNA synthesis techniques.



Within a cell, the DNA double strand is separated in segments during the copying process. One of the single strands serves as the “master copy” or template. Polymerase enzymes snap together the corresponding nucleotides stepwise to form the new complementary strand, beginning with a “starting segment” known as a primer. The backbone of a DNA strand is an alternating chain of five-membered sugar rings and phosphate groups. The chain links are formed at the 3’ and 5’ oxygen atoms of the sugars; natural growth occurs in the 3’ direction.

One question relating to the origin of life is: How was nature able to copy DNA or RNA strands before polymerases existed? Since the 1980s, DNA synthesizers have allowed chemists to produce DNA strands, but without a template or primer; the sequence is determined by the order of addition of the reagents.

Only the use of protective groups that inhibit uncontrolled reactions and the programmed addition of the reagents ensure that the sequence of bases is correct. This is clearly not how nature does it. But how could template-directed primer extension function purely chemically, with no enzymes?

More recently, different approaches have been used to develop a method called chemical primer extension, which involves the reaction of activated nucleotides with the end of a slightly modified DNA primer. Clemens Richert, Andreas Kaiser, and Sebastian Spies of the University of Stuttgart (Germany) have now developed this method further.

They found a protective group that can be removed under gentle conditions so that the DNA duplexes made from the primer and template do not fall apart. This allows the reactivity of the nucleotides and the terminus of the primer to be switched on and off as desired, and the sequence information in the template strand can be read out nucleotide by nucleotide. For this method to work, the template and primer are both attached to tiny spheres. As in an automated synthesizer, the reagents and building blocks can flow over the spheres.

The primer is bound to the template through base pairing. A suitable nucleotide from the surrounding solution docks at the next vacant binding site of the template. The nucleotide then binds to the reactive end of the primer through activated phosphate units. The sites that are supposed to react are chemically altered to become more reactive than in natural DNA. The special thing about this method is that the chain extension can be controlled to occur in either the 3’ or the 5’ direction. This is not known to take place in nature.

So far, this process has remained quite slow and is limited to short sequences. Improvement should be possible through optimization of the reaction conditions and better automation.

About the Author
Clemens Richert is a Professor of Biological Chemistry at the Institute of Organic Chemistry at the University of Stuttgart. His research is focused on nucleic acids, and he is investigating molecular recognition, chemical replication processes, and the development of novel nanomaterials.
Author: Clemens Richert, Universität Stuttgart (Germany), http://chip.chemie.uni-stuttgart.de/members.html
Title: Template-Directed Synthesis in 3′- and 5′-Direction with Reversible
Angewandte Chemie International Edition 2012, 51, No. 33, 8299–8303, Permalink to the article: http://dx.doi.org/10.1002/anie.201203859

Clemens Richert | Angewandte Chemie
Further information:
http://pressroom.angewandte.org
http://chip.chemie.uni-stuttgart.de/members.html

Further reports about: Angewandte Chemie DNA DNA strand building block oxygen atom

More articles from Life Sciences:

nachricht New risk factors for anxiety disorders
24.02.2017 | Julius-Maximilians-Universität Würzburg

nachricht Stingless bees have their nests protected by soldiers
24.02.2017 | Johannes Gutenberg-Universität Mainz

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Stingless bees have their nests protected by soldiers

24.02.2017 | Life Sciences

New risk factors for anxiety disorders

24.02.2017 | Life Sciences

MWC 2017: 5G Capital Berlin

24.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>