When green algae "can't breathe", they get rid of excess energy through the production of hydrogen. Biologists at the Ruhr-Universität Bochum have found out how the cells notice the absence of oxygen. For this, they need the messenger molecule nitric oxide and the protein haemoglobin, which is commonly known from red blood cells of humans. With colleagues at the UC Los Angeles, the Bochum team reported in the journal "PNAS".
Haemoglobin – an old protein in a new look
In the human body, haemoglobin transports oxygen from the lungs to the organs and brings carbon dioxide, which is produced there, back to the lungs. "However, scientists have known for years that there is not just the one haemoglobin", says Prof. Thomas Happe from the Work Group Photobiotechnology. Nature has produced a large number of related proteins which fulfil different functions. The green alga Chlamydomonas reinhardtii has what is known as a "truncated" haemoglobin, the function of which was previously unknown. Happe's team has deciphered its role in surviving in an oxygen-free environment.
In an oxygen-free environment, the green alga activates specific genes
When Chlamydomonas has no oxygen available, the algae transfer excess electrons to protons, creating hydrogen (H2). "For this to work, the green alga activates a certain gene programme and creates many new proteins", Happe explains. "But how exactly the cells even notice that oxygen is missing is something we did not know." The research team looked for genes that are particularly active when green algae have to live without oxygen – and found a gene that forms the blueprint for a haemoglobin. In an oxygen-rich environment, however, this gene was completely idle.
A haemoglobin and nitric oxide help green algae to survive
The scientists studied the haemoglobin protein and its genetic blueprint in more detail using molecular biological and biochemical analyses. "One thing became clear very quickly", says Dr. Anja Hemschemeier from the Work Group Photobiotechnology. "Algae in which we switched this gene off could hardly grow without oxygen." From previous studies it is known that in many organisms, haemoglobin detoxifies nitric oxide, because an overdose of this gas poisons the cells. The biologists therefore tested whether green algae which are no longer able to form haemoglobin after genetic manipulation die of nitric oxide poisoning. Their expectations: the green algae should fare better if the gas is removed using a chemical scavenger. "Surprisingly, then the algae were not able to grow at all", says Hemschemeier. The researchers concluded that, under oxygen-free conditions, haemoglobin and nitric oxide are in cahoots.
Nitric oxide signals: "no oxygen!"
Nitric oxide acts in many living organisms as a signalling molecule – apparently also in green algae. Experiments in vitro have shown that the green algal haemoglobin interacts with nitric oxide. When the researchers artificially introduced the gas to the single cell organisms, certain genes became active that are otherwise only "turned on" in the absence of oxygen. "From all this data we can conclude that Chlamydomonas uses nitric oxide to pass on the 'no oxygen!' signal within the cell, and that our haemoglobin is involved in this process", Happe sums up. His team wants to go on exploring the role of this protein in green algae, as the biologists have discovered another eleven haemoglobin genes in the organism. "Now things are really getting going", says the Bochum scientist. "The map of haemoglobin research has many blank spots that we want to fill with content. The fact that a single cell requires twelve haemoglobin proteins indicates that these fulfil finely tuned functions in the cell."
A. Hemschemeier, M. Düner, D. Casero, S.S. Merchant, M. Winkler, T. Happe (2013): Hypoxic survival requires a 2-on-2 hemoglobin in a process involving nitric oxide, Proceedings of the National Academy of Sciences, doi: 10.1073/pnas.1302592110
Three images related to this press release can be found online at: http://aktuell.ruhr-uni-bochum.de/pm2013/pm00181.html.en
Prof. Dr. Thomas Happe, Work Group Photobiotechnology, Department of Plant Biochemistry, Faculty of Biology and Biotechnology at the Ruhr-Universität, 44780 Bochum, Germany, Tel. +49/234/32-27026, E-mail: firstname.lastname@example.org
Dr. Anja Hemschemeier, Work Group Photobiotechnology, Department of Plant Biochemistry, Faculty of Biology and Biotechnology at the Ruhr-Universität, 44780 Bochum, Germany, Tel. +49/234/32-24282, E-mail: email@example.com
Editor: Dr. Julia Weiler
Dr. Thomas Happe | EurekAlert!
Further reports about: > Biochemistry > Biotechnology > Chlamydomonas reinhardtii > Haemoglobin > Photobiotechnology > blood cell > green algae > haemoglobin detoxifies nitric oxide > living organism > molecule nitric oxide > nitric oxide > oxygen-free environment > red blood cells > single cell > specific gene > synthetic biology
Water forms 'spine of hydration' around DNA, group finds
26.05.2017 | Cornell University
How herpesviruses win the footrace against the immune system
26.05.2017 | Helmholtz-Zentrum für Infektionsforschung
Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.
Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....
Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.
The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....
An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.
We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...
Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.
Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...
An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...
24.05.2017 | Event News
23.05.2017 | Event News
22.05.2017 | Event News
26.05.2017 | Life Sciences
26.05.2017 | Life Sciences
26.05.2017 | Physics and Astronomy