Skip to ContentSkip to Navigation
About usNews and EventsNews articles

The biology of peroxisomes in Hansenula polymorpha

15 September 2008

PhD ceremony: B. de Vries, 16.15 uur, Academiegebouw, Broerstraat 5, Groningen

Thesis: The biology of peroxisomes in Hansenula polymorpha

Promotor(s): prof. M. Veenhuis, prof. I.J. van der Klei

Faculty: Mathematics and Natural Sciences

 

Bart de Vries studied a peroxisomal membrane proteins, Pex14p. This protein is of importance for both the creation (biogenesis) as well as degradation (macropexophagy) of the peroxisome. We make a distinction between two types of peroxisomes in Hansenula polymorpha, ie. Mature organelles, which are in essence just “protein bags” wherein the enzymatic reactions take place and the young peroxisomes that actively import peroxisomal matrix proteins to grow.

Minute amounts of Pex14p suffice for macropexophagy, while this is insufficient for correct biogenesis. Pex14p may act as a switch at the moment macropexophagy is induced, this can explain why this minute amount of Pex14p is sufficient.

Furthermore we analyzed the roll of the first (conserved in all organisms) stretch of amino acids in Pex14p and their importance for the import of two classes of peroxisomal matrix proteins. We show here that two residues are essential for both types of matrix proteins as well as the shape of the protein in this stretch of amino acids.

We also studied the roll of a cytosolic SNARE protein in both biogenesis of peroxisomes and macropexophagy. In the absence of this protein, misshapen peroxisomes are formed, yet this does not affect the capability of the cells to grow like wild type op methanol. The cell is however, not capable of degrading these aberrant peroxisomes.

Finally, an in silico study of the genoom of H. polymorpha and Pichia pastoris resulted in 34 possible new putative peroxisomal proteins. An acetylspermidine oxidase with a deviant signal sequence was tested as a “proof-of-principle” for its localization and was found solely in the peroxisome.

 

Last modified:15 September 2017 3.37 p.m.

More news

  • 23 April 2019

    From paperclip to patent

    How is it possible that an albatross doesn’t crash and die when it lands? And how come its large wings don’t break due to air resistance? That is what you would expect, according to the laws of aerodynamics. However, Professor Eize Stamhuis has discovered...

  • 17 April 2019

    Why lightning often strikes twice

    In contrast to popular belief, lightning often does strike twice, but the reason why a lightning channel is ‘reused’ has remained a mystery. Now, an international research team led by the University of Groningen has used the LOFAR radio telescope to...

  • 16 April 2019

    Still going strong after four decades

    On March 29th professor of Applied Physics Jeff de Hosson was offered a farewell symposium, a few months after his official retirement date near the close of 2018. ‘But 29 March was the 100th birthday of Jan Francken, my predecessor.’ Besides, De Hosson...