Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

A molecular identity crisis - a "Ribozyme without RNA"

03.11.2008
Not all enzymes that are assumed to require an RNA component in order to function do actually contain RNA.
This surprising discovery was made during a project supported by the Austrian Science Fund FWF that focussed on the enzyme RNase P. Contrary to accepted scientific theory, the project team from Vienna has long believed that certain forms of RNase P do not contain any RNA. They have now succeeded in proving their point through a series of sophisticated experiments, the results of which are being published today in the journal CELL.

Although ribozymes are not quite living fossils, these enzymes - which function only in the presence of RNA - hail from a long gone age when biochemical processes were still controlled by RNA molecules. It was only later that proteins came onto the molecular scene. RNase P, an enzyme that modifies transfer RNAs, is one such RNA enzyme (ribozyme). All previously characterised forms of this enzyme confirmed assumptions about their RNA component. Nevertheless, evidence has also been uncovered over the past 20 years that has cast doubt on the universality of this finding and indicated that this enzyme could be made up solely of proteins. The experts certainly had plenty to debate.

RNA NOT ALWAYS ESSENTIAL
But the debate seems to have been brought to an end. A group headed by Prof.
Walter Rossmanith at the Medical University of Vienna has provided conclusive evidence by successfully identifying the components of human mitochondrial RNase P. Prof. Rossmanith: "RNase P is made up of three proteins that are solely responsible for the catalytic capacity of the enzyme without any RNA. This discovery has not been made before because the enzyme breaks down easily during purification due to the loose connection between its components. The approach we developed enabled us to get around this problem. That was the breakthrough that enabled us to identify the proteins." Johann Holzmann, a PhD student and member of Prof. Rossmanith's team, explains further: "The most difficult task was to track down the proteins. Everything started to move much faster once we had done that. We produced the individual proteins separately in bacteria, purified them and then used them to reconstitute mitochondrial RNase P in vitro. This finally removed any shadow of doubt for us - and CELL: mitochondrial RNase P does not contain RNA."

REINVENTING THE WHEEL

The identification of the three proteins also resolved another previously unanswered question in molecular evolution research: How is a ribozyme replaced by a protein enzyme? The answer provided by data collected during the project is that the protein-only mitochondrial RNase P developed in parallel to a pre-existing ribozyme. Eventually, it replaced the latter. It is interesting to note that the three protein components have been recruited from entirely different biochemical pathways and yet they have nevertheless retained their original functions. Prof. Rossmanith adds: "We are also calling mitochondrial RNase P a patchwork enzyme, because it seems to be assembled from components available by chance at the time of its appearance in evolution." It is still unclear why only animal mitochondrial RNase P and not all ribozymes have been replaced by protein enzymes. Indeed, the results of this successful FWF project have opened the door to a whole range of questions - and answers.

Original publication:
"RNase P without RNA: Identification and functional reconstitution of the human mitochondrial tRNA processing enzyme"
J. Holzmann, P. Frank, E. Löffler, K. Bennett, C. Gerner & W. Rossmanith.
Cell 135, 462-474, October 31, 2008, DOI 10.1016/j.cell.2008.09.013


Scientific Contact:
Walter Rossmanith, PhD Medical
University of Vienna
Center for Anatomy & Cell Biology
Währingerstr. 13
1090 Vienna
Austria
M 0664 / 800 16 37 512
E walter.rossmanith@meduniwien.ac.at
Austrian Science Fund FWF:
Mag. Stefan Bernhardt
Haus der Forschung
Sensengasse 1
1090 Vienna
Austria
T +43 / 1 / 505 67 40 - 8111
E stefan.bernhardt@fwf.ac.at
Editing & Distribution:
PR&D - Public Relations for Research & Education Campus Vienna Biocenter 2 1030 Vienna Austria T +43 / 1 / 505 70 44 E contact@prd.at W http://www.prd.at

Ramona Seba | PR&D
Further information:
http://www.fwf.ac.at
http://www.meduniwien.ac.at
http://www.fwf.ac.at/en/public_relations/press/pv200811-en.html

More articles from Life Sciences:

nachricht A novel socio-ecological approach helps identifying suitable wolf habitats
17.02.2017 | Universität Zürich

nachricht New, ultra-flexible probes form reliable, scar-free integration with the brain
16.02.2017 | University of Texas at Austin

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

Switched-on DNA

20.02.2017 | Materials Sciences

Second cause of hidden hearing loss identified

20.02.2017 | Health and Medicine

Prospect for more effective treatment of nerve pain

20.02.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>