Bochum and Dortmund-based researchers discover new function in an old acquaintance
What drives peroxisomes to degrading pollutants
Essential: importing enzymes into peroxisome
Peroxisomes are of vital importance for the enzymatic degradation of long-chain fatty acids and cellular toxins. In order for them to fulfil this function, the relevant enzymes have to be imported into the peroxisomes first. The bulk is brought into a peroxisome by the import receptor Pex5p. That receptor, in turn, is regulated by the protein ubiquitin (Ub): the modification of the receptor with an Ub-molecule paves the way for a new import reaction for further enzymes that have to be transported into the peroxisome.
Misjudged as anchor
In their previous projects, the team of Jun.-Prof. Harald Platta, Dr. Fouzi El Magraoui and Prof. Ralf Erdmann has already defined the basic composition of the peroxisomal Ub-machinery. They identified six related proteins and subdivided them into three functionally diverse groups. "It has remained unclear, however, how that molecular machinery is activated resp. how its activity is boosted," explains Harald Platta. In the current study, the researchers have succeeded in identifying the module that fulfils this vital function. "To our surprise, it's turned out to be not a hitherto unknown protein, but the component of a familiar protein, the already identified Pex22p," says Platta. "We have previously assumes that Pex22p's function is limited to being an anchor protein and that, by binding the soluble Pex4p to the membrane of the peroxisomes, it supports its function indirectly."
Research based on the modular concept
In order to ascertain which components are relevant, the researchers deployed the modular concept to assemble them by means of genetic fusions in various combinations. In doing so, they found out that the membrane anchor component of Pex22p was entirely irrelevant, provided that the soluble Pex4p was bound to the peroxisome at the membrane anchor component of Pex3p that was not functionally involved in the import reaction. This combination shows a low Ub-activity, which is too insignificant to modify a sufficient number of import receptors and to trigger the import of enzymes into the peroxisome. It isn't until Pex22(C) is added that Ub-activity increases, thus enabling the import of a sufficient number of enzymes into the peroxisome, in order to guarantee the peroxisome's functionality.
Not merely looking for new components, but also revising familiar ones
The discovery of this "accelerator" of the peroxisomal Ub machinery and – linked to it – the import machinery is relevant not just for understanding peroxisomal disorders such as the Zellweger syndrome. "It turns out that certain central proteins can fulfil several important tasks in biochemical systems in general," explains Harald Platta. "When analysing the molecular basis of various biochemically defined disorders, it will become relevant in general to identify a system's lacking activities not just by searching for new, unknown proteins. Our study demonstrates that a lacking function such as this may be perhaps already 'concealed’ in a familiar protein."
El Magraoui et al.: The cytosolic domain of Pex22p stimulates the Pex4p-dependent ubiquitination of the PTS1-receptor. In: PLoS One, 9(8): e105894. doi:10.1371/journal.pone.0105894
Dr. Harald Platta | Eurek Alert!
Novel mechanisms of action discovered for the skin cancer medication Imiquimod
21.10.2016 | Technische Universität München
Second research flight into zero gravity
21.10.2016 | Universität Zürich
Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.
"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...
In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.
A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...
By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.
"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...
COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.
In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...
'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.
Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...
14.10.2016 | Event News
14.10.2016 | Event News
12.10.2016 | Event News
21.10.2016 | Health and Medicine
21.10.2016 | Information Technology
21.10.2016 | Materials Sciences