q&more
My watch list
my.chemie.de  
Login  

News

How multicellular cyanobacteria transport molecules

ETH Zürich

The connections between cells of an Anabaene cell formation are furnished with numerous special channels (light green).

16-Jul-2019: Researchers from ETH Zurich and the University of Tübingen have taken a high-resolution look at the structure and function of cell-to-cell connections in filamentous, multicellular cyanobacteria. This enables them to explain how these microorganisms regulate the transport of various substances between the individual cells.

Also known as blue-green algae, cyanobacteria are a special class of bacteria that are able to perform photosynthesis. In evolutionary terms, they are ancient. Their predecessors – which first emerged on earth some 2.5 billion years ago – paved the way for higher forms of life thanks to their ability to produce oxygen by photosynthesis.

Some cyanobacterial species are filamentous, multicellular organisms that have developed differentiated cell functions. Some cells perform photosynthesis, while others absorb atmospheric nitrogen. The cyanobacteria obtain energy in the form of glucose through photosynthesis; they use the nitrogen to produce amino acids, the building blocks of proteins.

For the cyanobacteria, this poses the problem of how the individual cells can communicate and exchange substances. The photosynthetic cells have to keep their nitrogen-fixing sister cells supplied with glucose; by the same token, amino acids need to be transported in the opposite direction. To this end, cyanobacteria have developed special cell junctions that permit the exchange of nutrients and messengers across cell boundaries, without the cells being fused together.

Elucidating the structure in cellular context

To date, very little was known about the detailed structure and precise functioning of the cell junctions in multicellular, filamentous cyanobacteria. In the latest issue of the scientific journal Cell, a group of researchers from ETH Zurich and the University of Tübingen presents an unprecedented degree of detail on the structure and function of the cell-to-cell connections, referred to as septal junctions, in the Anabaena genus.

The researchers reveal that the connecting channels are composed of a protein tube that is sealed with a plug at both ends. Moreover, this tube is covered with five-armed protein elements, which are arranged much like a camera aperture.

The channels connect the cytoplasms of two neighbouring cells by passing through the different membranes and cell walls. The cells are separated by an ultra-thin gap, just a few nanometres wide.

“Researchers have so far failed to clarify these details with conventional electron microscopy. By extending cryo-electron microscopy, we were able to gain a degree of precision never before achieved,” says Professor Martin Pilhofer from the Institute of Molecular Biology and Biophysics at ETH Zurich.

Gregor Weiss, Pilhofer’s doctoral student, developed a process of preparing the cyanobacteria in such a way that the channels could be visualised via cryo-electron microscopy. Using frozen cyanobacteria, Weiss “milled” the junction between two cells, layer by layer, until his sample was thin enough. Without this pre-processing, the spherical cells would have been too thick for cryo-electron microscopy.

Mechanism to prevent leaking

“Due to the complex structure of the connecting channels, we suspected there was a mechanism to open and close them,” said Karl Forchhammer, Professor for Microbiology at the University of Tübingen. He and his team were in fact able to show how the cells of the complex communicate with each other under different stress conditions. They stained cyanobacteria chains with a fluorescent dye and then bleached individual cells with a laser. The researchers then measured the influx of the dye from neighbouring cells.

Using this method, they were able to show that the channels actually close when treated with chemicals or in the dark. The filigree cap structure of a channel closes like an iris and interrupts the exchange of substances between the cells; the researchers recognised this phenomenon through the varying degree of fluorescence they observed.

“This closing mechanism protects the entire multicellular organism,” Forchhammer says. For example, it can prevent a cell from passing on harmful substances to its neighbouring cells, which could destroy the whole organism. The cyanobacteria can also use the channels to prevent the cell contents of the entire network from leaking out if individual cells are mechanically damaged.

Conserved structures

With their study, the researchers are able to show that in the course of evolution, multicellular organisms of different lineages repeatedly and independently “invented” cell junctions. “It emphasises just how important it is for a multicellular organism to be able to monitor the transport of substances between its individual cells,” Pilhofer says. By elucidating the channel structure and function in cyanobacteria, the ETH researchers are adding another piece to the puzzle. “As far as we are concerned, this is fundamental biological research, without focusing on any potential application. The new data rather gives us a greater understanding of the evolution of complex life forms,” the ETH professor explains.

Original publication:
Weiss GL, Kieninger A-K, Maldener I, Forchhammer K, Pilhofer M.; "Structure and function of a bacterial gap junction analog"; Cell; 2019, July 11th.

Facts, background information, dossiers

  • cyanobacteria
  • cells
  • cryo-electron microscopy

More about ETH Zürich

  • News

    When sand behaves like oil

    Sand, coffee grounds and rice behave very differently than water or oil, but under certain conditions they will suddenly exhibit astonishing similarities. Scientists have found a way to better understand the behaviour of granular materials. Sand, rice and coffee are all examples of granular ... more

    Fleming’s method in miniature

    Scientists in the Department of Biosystems Science and Engineering at ETH Zurich in Basel have developed a method with which they can quickly test a very large number of molecules for antibiotic effect. With it, they have already successfully discovered new antibiotic candidates produced by ... more

    Bacteria reveal strong individuality when navigating a maze

    Researchers from ETH Zurich demonstrate that genetically identical cells exhibit differing responses in their motility towards chemical attractants. Average values hide the full picture when it comes to describing the behaviour of bacteria. Although they are considered the simplest of all l ... more

  • q&more articles

    Analysis in picoliter volumes

    Reducing time, costs and human resources: many basic as well as applied analytical and diagnostic challenges can be performed on lab-on-a-chip systems. They enable sample quantities to be reduced, work steps to be automated and completed in parallel, and are ideal for combination with highl ... more

    Investment for the Future

    This is a very particular concern and at the same time the demand placed annually on Dr. Irmgard Werner, who, as a lecturer at the ETH Zurich, supports around 65 pharmacy students in the 5th semester practical training in “pharmaceutical analysis”. With joy and enthusiasm for her subject sh ... more

  • Authors

    Prof. Dr. Petra S. Dittrich

    Petra Dittrich is an Associate Professor in the Department of Biosystems Science and Engineering at ETH Zurich (Switzerland). She studied chemistry at Bielefeld University and the University of Salamanca (Spain). After completing her doctoral studies at the Max Planck Institute for Biophysi ... more

    Dr. Felix Kurth

    Felix Kurth studied bioengineering at the Technical University Dortmund (Germany) and at the Royal Institute of Technology in Stockholm (Sweden). During his PhD studies at ETH Zurich (Switzerland), which he completed in 2015, he developed lab-on-a-chip systems and methods for quantifying me ... more

    Lucas Armbrecht

    Lucas Armbrecht studied microsystems technology at the University of Freiburg (Breisgau, Germany). During his master’s, he focused on sensors & actuators and lab-on-a-chip systems. Since June 2015, he is PhD student in the Bioanalytics Group at ETH Zurich (Switzerland). In his doctoral stud ... more

More about Universität Tübingen

  • News

    How sleep strengthens the immune system

    Getting enough sleep is vital to supporting our immune system in fighting off pathogens – so much is common knowledge. But what we don't know is how exactly sleep affects certain immune functions. Scientists at the University of Tübingen and the University of Lübeck have now discovered a ne ... more

    Natural substance as alternative to controversial glyphosate?

    Researchers at the University of Tübingen have discovered a natural substance that could compete with the controversial herbicide glyphosate: The newly discovered sugar molecule synthesized from cyanobacteria inhibits the growth of various microorganisms and plants but is harmless to humans ... more

    Breakthrough in the investigation of feared pathogens

    Researchers at the University of Tübingen and the German Center for Infection Research (DZIF) have achieved a breakthrough in the decoding of multi-resistant pathogens. The team led by Professor Andreas Peschel and Professor Thilo Stehle was able to decode the structure and function of a pr ... more

  • q&more articles

    Putting Pressure on Pharmaceuticals

    As a general rule, the pharmaceuticals industry develops new drugs by applying a complex procedure of formulation utilising excipients suitable for the final drug dosage form. Such development processes are carried out by the companies’ technical departments and in many cases result in solu ... more

    Staying power

    Geoscientists, biologists and chemists at the University of Tübingen are working in collaboration with IFAM (Fraunhofer Institute for Manufacturing Technology and Advanced Materials in Bremen, Germany) to uncover the workings of insect surface adhesion. The goal of this project is the synth ... more

  • Authors

    Prof. Dr. Michael Lämmerhofer

    Michael Lämmerhofer studied pharmacy at the University of Graz, receiving his doctorate in pharmaceutical chemistry in 1996. This was followed by a move to the University of Vienna, where, with the exception of a one-year postdoc at the University of Berkeley (from 1999 to 2000), his positi ... more

    Heike Gerhardt

    Heike Gerhardt studied chemistry at the universities of Tübingen and Vienna, already choosing to specialize in analysis during her master’s degree at the University of Vienna. She has worked at the University of Tübingen under Prof. Lämmerhofer since 2012: with her doctoral research work ne ... more

    Prof. Dr. Martin A. Wahl

    studied pharmacy at the University of Tübingen and was awarded his doctorate in 1984. Following a one-year period of research at the Karolinska Institutet in Stockholm, he completed his habilitation in pharmacology and toxicology in 1995. In 1998, he moved to the University of Tübingen’s Ph ... more

q&more – the networking platform for quality excellence in lab and process

The q&more concept is to increase the visibility of recent research and innovative solutions, and support the exchange of knowledge. In the broad spectrum of subjects covered, the focus is on achieving maximum quality in highly innovative sectors. As a modern knowledge platform, q&more offers market participants one-of-a-kind networking opportunities. Cutting-edge research is presented by authors of international repute. Attractively presented in a high-quality context, and published in German and English, the original articles introduce new concepts and highlight unconventional solution strategies.

> more about q&more

q&more is supported by:

 

Your browser is not current. Microsoft Internet Explorer 6.0 does not support some functions on Chemie.DE