Discovery of a novel peroxisomal function for biotin biosynthesis in Aspergillus oryzae

Ref ID: 18450

Author:

Jun-Ichi Maruyama, Yasuko Tanabe, Daiki Yahagi, Ichiro Matsuo, Katsuhiko Kitamoto

Author address:

The University of Tokyo, Gunma University  

Full conference title:

11 th European Conference on Fungal Genetics

Abstract:

Peroxisomes, ubiquitous organelles in eukaryotic cells, typically contain enzymes involved in β 8208;oxidation of fatty
acids, and play diverse roles in different eukaryotic organisms. In filamentous fungi, for example, they are required
for the formation of Woronin body that is an organelle specific to filamentous ascomycetes and functions in the
septal pore plugging upon hyphal injury. Furthermore, peroxisomes are reported to play fundamental roles during
growth in humans, plants and also filamentous fungi. However, molecular mechanisms responsible for the severe
growth defects of peroxisomal deficiency remain unknown.
Here we generated the Aspergillus oryzae strains with deleted Aopex5 and Aopex7 genes encoding the receptors
for peroxisomal targeting signals PTS1 and PTS2, respectively. In addition to their growth defects in the minimal
medium containing oleic acid as a carbon source, surprisingly, they exhibited growth defects on the glucose
medium. By screening for required nutrient supplements, we found that the addition of biotin restores their
growth defects. Genome database searches revealed that BioF protein/KAPA (78208;keto8208;88208;aminopelargonic acid)
synthase, one of the biotin biosynthetic enzymes, has a PTS1 sequence. Both  916;AobioF and AobioF916;PTS1 strains
exhibited growth defects in the absence of biotin, indicating that peroxisomal targeting of BioF is crucial for the
biotin biosynthesis.
In conclusion we demonstrate a novel role for peroxisomes in biotin biosynthesis, of which steps are upstream of
the terminal reactions in mitochondria.

Abstract Number: PR1.11

Conference Year: 2012

Link to conference website: http://www.ecfg.info/images/Abstract_Book_Electronic.pdf

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