Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Making sure antibiotics work as they should

09.10.2014

Researchers at ETH Zurich are decoding the structure of the large ribosomal subunit of the mitochondria at an atomic level, thereby providing insight into the molecular architecture of this ribosome with implications for a better understanding of the mode of action of antibiotics.


Detail of the structure of the large subunit of the mitochondrial ribosome in mammals. (Source: Chair N. Ban / ETH Zurich)

A team of ETH Zurich researchers led by professors Nenad Ban and Ruedi Aebersold have studied the highly complex molecular structure of mitoribosomes, which are the ribosomes of mitochondria. Ribosomes are found in the cells of all living organisms.

However, higher organisms (eukaryotes), which include fungi, plants, animals and humans, contain much more complex ribosomes than bacteria. In eukaryotes, ribosomes can also be divided into two types: those in the cytosol – which comprises the majority of the cell – and those found in the mitochondria or “power plants” of cells. Mitochondria are only found in eukaryotes.

Ribosomes serve as translation devices for the genetic code and produce proteins based on the information stored in DNA. Every ribosome consists of two subunits. The smaller subunit uses transfer ribonucleic acids (transfer RNA or tRNA) to decode the genetic code it receives in the form of messenger RNA, while the larger subunit joins the amino acids delivered by the transfer RNA together like a string of pearls.

Even higher resolution, even more details

Mitochondrial ribosomes are especially difficult to study because they are found only in small amounts and are difficult to isolate. At the beginning of the year, ETH researchers had shed light on the molecular structure of the large subunit of the mitoribosome in mammalian cells to a resolution of 4.9 Å (less than 0.5 nm).

However, this resolution was not adequate to reliably build a complete atomic model of this previously unknown structure. The team lead by ETH Professor Nenad Ban has now succeeded in this task and was able to map the entire structure at a resolution of 3.4 Å (0.34 nm). The researchers recently published their findings in the scientific journal Nature.

The scientists used high-resolution cryo-electron microscopy at the Electron Microscopy Center of ETH Zurich (ScopeM) and state-of-the-art mass spectrometry methods in their experiments. Thanks to recent technical advances in cryo-electron microscopy and the development of direct electron detection cameras that can correct for specimen motion during the exposure, it only recently became possible to capture images of biomolecules at a resolution of less than four angstroms.

Improving the effect of antibiotics

In particular, the new images show the details of the peptidyl transferase centre (PTC), which is where the amino acid building blocks are combined. The proteins synthesised in this way then pass through a tunnel, where they finally exit the large subunit of the ribosome.

“This process is medically relevant,” said Basil Greber, lead author of the study and postdoctoral researcher in Nenad Ban's group. The reason is that this tunnel is a target for certain antibiotics. The antibiotic becomes lodged in the tunnel and prevents the proteins that have just been synthesized from leaving the tunnel. However, antibiotics should only inhibit protein synthesis in the ribosomes of bacteria.

“For an antibiotic to be used in humans, it must not attack human ribosomes,” explains Greber. Antibiotics must inhibit protein synthesis only in bacterial ribosomes. The problem is that mitochondrial ribosomes resemble those of bacteria, which is why certain antibiotics also interfere with mitoribosomes. “This can lead to serious side effects.” The ETH researchers' findings will make it possible in the future to design antibiotics that inhibit only bacterial and not mitochondrial ribosomes. This is one basic requirement for using them in clinical applications.

A surprising discovery

The ETH researchers also made an unexpected discovery. They found that mitoribosomes use transfer RNA in two fundamentally different ways. Firstly, the tRNA is used to select the right amino acid for peptide synthesis in the PTC. Secondly, one tRNA is a fixed part of the structure, unlike in all other ribosomes. Although it has been known for quite some time that mitochondrial ribosomes integrated new proteins into their structure over the course of their development, this is the first time that the use of an entirely new RNA molecule was observed. “This demonstrates the great evolutionary plasticity of mitoribosomes,” underscored Greber.

The ETH team is now faced with a major, still unresolved task in its research: determining the structure of the smaller subunit of the mitochondrial ribosome. The fact that it is more flexible than the large subunit renders this undertaking an even greater challenge.

Literature reference

Greber BJ, Boehringer D, Leibundgut M, Bieri P, Leitner A, Schmitz N, Aebersold R, Ban N: The complete structure of the large subunit of the mammalian mitochondrial ribosome. Nature, o nline publication 1 Oktober 2014. doi: 10.1038/nature13895 

Greber B et al.: Architecture of the large subunit of the mammalian mitochondrial ribosome. Nature 2014, 505: 515–519. doi: 10.1038/nature12890 

Nenad Ban | Eurek Alert!
Further information:
https://www.ethz.ch/en/news-and-events/eth-news/news/2014/10/making-sure-antibiotics-work-as-they-should.html

More articles from Life Sciences:

nachricht Scientists unlock ability to generate new sensory hair cells
22.02.2017 | Brigham and Women's Hospital

nachricht New insights into the information processing of motor neurons
22.02.2017 | Max Planck Florida Institute for Neuroscience

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

Microhotplates for a smart gas sensor

22.02.2017 | Power and Electrical Engineering

Scientists unlock ability to generate new sensory hair cells

22.02.2017 | Life Sciences

Prediction: More gas-giants will be found orbiting Sun-like stars

22.02.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>