Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Sweet surprises

03.05.2010
By characterizing the sugar content of cells, researchers have begun to reconstruct important ‘quality control’ mechanisms for protein production

By characterizing the sugar content of cells, researchers have begun to reconstruct important ‘quality control’ mechanisms for protein production

Many proteins undergo N-glycosylation, in which they are decorated with combinations of carbohydrates. These modifications not only contribute directly to normal protein function but also act as a flag for defective proteins, which get steered into a pathway known as endoplasmic reticulum-associated degradation (ERAD) with the assistance of enzymes that remove glycosylations to release free oligosaccharides (fOSs).

As an undergraduate, Tadashi Suzuki discovered the enzyme peptide:N-glycanase (PNGase) in the cytosol of mammalian cells; now, as a team leader at the RIKEN Advanced Science Institute, Wako, his group has uncovered valuable details about this enzyme’s critical contribution to the early stages of ERAD.

Suzuki and postdoctoral researcher Hiroto Hirayama recently turned to brewer’s yeast, a popular model organism, as a means to study an enigmatic PNGase-independent pathway for fOS production initially identified in mammalian cells. To achieve this, they developed an approach to selectively isolate these molecules, combining chemical labeling of oligosaccharides with a method for eliminating background contamination from â-1,6-glucans, a component of the yeast cell wall.

This strategy yielded a full library of yeast cytosolic fOSs—and some unexpected results. “To our surprise, we only detected PNGase-dependent fOSs under our experimental conditions,” says Suzuki. “This clearly indicates that mechanisms for generation of fOSs are quite distinct between mammals and yeast.”

To ensure that the full range of fOS diversity was represented, they performed their analysis in yeast lacking expression of the cytosol/vacuolar á-mannosidase (Ams1p), the only enzyme known to break down fOSs. “Very sophisticated and complicated glycan-recognition mechanisms for ERAD have been uncovered, but these conclusions have been drawn using a few model proteins,” says Suzuki. “On the other hand, we analyzed the whole population of fOSs, which means we can get information about glycan structures for all ERAD substrates.”

These data revealed that misfolded proteins can undergo diverse modifications prior to ERAD, including glycosylation by an enzyme within the Golgi apparatus, a cellular structure in which proteins typically undergo their final modifications. This suggests the existence of a previously unidentified screening mechanism at this late stage in protein synthesis that selectively redirects misfolded molecules to the ERAD system.

These and other findings suggest a great deal of hidden complexity remaining to be uncovered, and Suzuki’s team is now analyzing yeast strains with mutations in various proteins that help ‘read’ and interpret protein glycosylations. “Hopefully, through comparative fOS analysis for these strains, we can provide more precise mechanisms for the role of N-glycans in ERAD,” he says.

The corresponding author for this highlight is based at the Glycometabolome Team, RIKEN Advanced Science Institute

Journal information

1. Hirayama, H., Seino, J., Kitajima, T., Jigami, Y. & Suzuki, T. Free oligosaccharides to monitor glycoprotein endoplasmic reticulum-associated degradation in Saccharomyces cerevisiae. The Journal of Biological Chemistry published online 20 February 2010 (doi: 10.1074/jbc.M109.082081)

gro-pr | Research asia research news
Further information:
http://www.rikenresearch.riken.jp/eng/research/6245
http://www.researchsea.com

More articles from Life Sciences:

nachricht How brains surrender to sleep
23.06.2017 | IMP - Forschungsinstitut für Molekulare Pathologie GmbH

nachricht A new technique isolates neuronal activity during memory consolidation
22.06.2017 | Spanish National Research Council (CSIC)

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Quantum thermometer or optical refrigerator?

23.06.2017 | Physics and Astronomy

A 100-year-old physics problem has been solved at EPFL

23.06.2017 | Physics and Astronomy

Equipping form with function

23.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>