Researchers discover giant pore in the membrane of peroxisomes

December 04, 2015

Researchers have discovered a second giant pore for the transport of folded proteins in certain cell organelles, i.e. peroxisomes. Five years ago, the group already described the first giant pore. The team headed by Prof Dr Ralf Erdmann from the Institute of Biochemistry and Pathobiochemistry at the Ruhr-Universität Bochum published the findings in the journal "Cell Reports" together with colleagues from Osnabrück, Bremen and Göttingen.

Import of folded proteins had baffled researchers for a long time

The functions of peroxisomes include, for example, the degradation of fatty acids and the elimination of toxic hydrogen peroxide in the cell. They contain numerous enzymes that they have to import from the cytoplasm. "For a long time, scientists had no understanding of how peroxisomes import large proteins," says Ralf Erdmann. "Especially since the proteins traverse the membrane in folded state." This means they are not transported in the form of a long chain of amino acids, but rather in their final three-dimensional configuration, the dimensions of which can be huge.

Two signal sequences mark proteins for the peroxisome

Proteins that are assigned to the peroxisomes carry certain signal sequencies. There are two types, namely PTS1 and PTS2. They are recognised by import receptors, which transport the folded proteins via a giant pore inside the peroxisomes. The pore that was discovered five years ago grants access to proteins with PTS1 sequences. The new pore is permeable to proteins with PTS2 sequences. Prior to the current study, it was considered that proteins with different signal sequences are imported via the same pore. Now, the researchers want to conduct a further study to figure out why separate import channels exist.

Pore is giant by cellular standards

"With a diameter of 4.5 nanometres, the PTS2 pore is giant by cellular standards," explains Prof Erdmann. The study, moreover, demonstrated that the channel has other properties than the PTS1 pore. For example, it is apparently unable to adjust its size to the protein that is to be transported. "However, in the model organism that we analysed the proteins transported via this channel did not exceed a certain size. Thus, size adjustment would have probably been an unnecessary luxury," assumes Erdmann. If the PTS2 transport channel malfunctions, the consequences for humans are fatal. Most patients die within the first year of life, often due to respiratory disorders.
-end-
Bibliographic record

M. Montilla-Martinez, S. Beck, J. Klümper,M. Meinecke,W. Schliebs, R. Wagner, R. Erdmann (2015): Distinct pores for peroxisomal import of PTS1 and PTS2 proteins, Cell Reports, DOI: 10.1016/j.celrep.2015.11.016

Further information

Prof Dr Ralf Erdmann, Systems Biochemistry, Faculty of Medicine at the Ruhr-Universität, 44780 Bochum, Germany, phone: +49/234/32-24943, email: Ralf.Erdmann@rub.de

One click away

Website of the Systems Biochemistry Department http://www.ruhr-uni-bochum.de/biochem/system/index.html.en

Research group PerTrans http://www.pertrans.org/index.html.en

Editorial Journalist: Dr Julia Weiler

Ruhr-University Bochum

Related Proteins Articles from Brightsurf:

New understanding of how proteins operate
A ground-breaking discovery by Centenary Institute scientists has provided new understanding as to the nature of proteins and how they exist and operate in the human body.

Finding a handle to bag the right proteins
A method that lights up tags attached to selected proteins can help to purify the proteins from a mixed protein pool.

Designing vaccines from artificial proteins
EPFL scientists have developed a new computational approach to create artificial proteins, which showed promising results in vivo as functional vaccines.

New method to monitor Alzheimer's proteins
IBS-CINAP research team has reported a new method to identify the aggregation state of amyloid beta (Aβ) proteins in solution.

Composing new proteins with artificial intelligence
Scientists have long studied how to improve proteins or design new ones.

Hero proteins are here to save other proteins
Researchers at the University of Tokyo have discovered a new group of proteins, remarkable for their unusual shape and abilities to protect against protein clumps associated with neurodegenerative diseases in lab experiments.

Designer proteins
David Baker, Professor of Biochemistry at the University of Washington to speak at the AAAS 2020 session, 'Synthetic Biology: Digital Design of Living Systems.' Prof.

Gone fishin' -- for proteins
Casting lines into human cells to snag proteins, a team of Montreal researchers has solved a 20-year-old mystery of cell biology.

Coupled proteins
Researchers from Heidelberg University and Sendai University in Japan used new biotechnological methods to study how human cells react to and further process external signals.

Understanding the power of honey through its proteins
Honey is a culinary staple that can be found in kitchens around the world.

Read More: Proteins News and Proteins Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.