Glucose-induced and nitrogen-starvation-induced peroxisome degradation are distinct processes in Hansenula polymorpha that involve both common and unique genes.
In the methylotrophic yeast Hansenula polymorpha non-selective autophagy, induced by nitrogen starvation, results in the turnover of cytoplasmic components, including peroxisomes. We show that the uptake of these components occurs by invagination of the vacuolar membrane without their prior sequestration and thus differs from the mechanism described for bakers yeast. A selective mode of autophagy in H. polymorpha, namely glucose-induced peroxisome degradation, involves sequestration of individual peroxisomes tagged for degradation by membrane layers that subsequently fuse with the vacuole where the organelle is digested. H. polymorpha pdd mutants are blocked in selective peroxisome degradation. We observed that pdd1-201 is also impaired in non-selective autophagy, whereas this process still normally functions in pdd2-4. These findings suggest that mechanistically distinct processes as selective and non-selective autophagy involve common but also unique genes.
Bellu
A R
AR
Eukaryotic Microbiology, Groningen Biomolecular Sciences, University of Groningen, P.O. Box 14, 9750 AA Haren, The Netherlands.
Kram
A M
AM
Kiel
J A
JA
Veenhuis
M
M
van der Klei
I J
IJ
D001343:Autophagy; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D005947:Glucose / Q000378:metabolism*; D000432:Methanol / Q000378:metabolism; D008854:Microscopy, Electron; D009584:Nitrogen / Q000378:metabolism*; D020675:Peroxisomes / Q000378:metabolism*; D010843:Pichia / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*
D005656:Fungal Proteins; C120506:Pdd1 protein, Hansenula; D005947:Glucose; D009584:Nitrogen; D000432:Methanol