title: Peroxisomes are involved in biotin biosynthesis in Aspergillus and Arabidopsis.
abstract: Among the eukaryotes only plants and a number of fungi are able to synthesize biotin. Although initial events leading to the biosynthesis of biotin remain largely unknown, the final steps are known to occur in the mitochondria. Here we deleted the Aopex5 and Aopex7 genes encoding the receptors for peroxisomal targeting signals PTS1 and PTS2, respectively, in the filamentous fungus Aspergillus oryzae. In addition to exhibiting defects in the peroxisomal targeting of either PTS1 or PTS2 proteins, the deletion strains also displayed growth defects on minimal medium containing oleic acid as the sole carbon source. Unexpectedly, these peroxisomal transport-deficient strains also exhibited growth defects on minimal medium containing glucose as the sole carbon source that were remediated by the addition of biotin and its precursors, including 7-keto-8-aminopelargonic acid (KAPA). Genome database searches in fungi and plants revealed that BioF protein/KAPA synthase, one of the biotin biosynthetic enzymes, has a PTS1 sequence at the C terminus. Fungal ΔbioF strains expressing the fungal and plant BioF proteins lacking PTS1 still exhibited growth defects in the absence of biotin, indicating that peroxisomal targeting of KAPA synthase is crucial for the biotin biosynthesis. Furthermore, in the plant Arabidopsis thaliana, AtBioF localized to the peroxisomes through recognition of its PTS1 sequence, suggesting involvement of peroxisomes in biotin biosynthesis in plants. Taken together we demonstrate a novel role for peroxisomes in biotin biosynthesis and suggest the presence of as yet unidentified peroxisomal proteins that function in the earlier steps of biotin biosynthesis.
authors: Department of Biotechnology, The University of Tokyo, Tokyo 113-8657.
authors: Yasuko
authors: Y
authors: Tanabe
authors: Department of Biotechnology, The University of Tokyo, Tokyo 113-8657. Electronic address: amarujun@mail.ecc.u-tokyo.ac.jp.
authors: Jun-Ichi
authors: JI
authors: Maruyama
authors: Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657; Graduate School of Science, Kyoto University, Kyoto 606-8502.
authors: Shohei
authors: S
authors: Yamaoka
authors: Department of Biotechnology, The University of Tokyo, Tokyo 113-8657.
authors: Daiki
authors: D
authors: Yahagi
authors: Department of Chemistry and Chemical Biology, Gunma University, Gunma 376-8515, Japan.
authors: Ichiro
authors: I
authors: Matsuo
authors: Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657.
authors: Nobuhiro
authors: N
authors: Tsutsumi
authors: Department of Biotechnology, The University of Tokyo, Tokyo 113-8657.
authors: Katsuhiko
authors: K
authors: Kitamoto
mesh_terms: D000596:Amino Acids / Q000494:pharmacology*; D017360:Arabidopsis / Q000378:metabolism*; D001236:Aspergillus oryzae / Q000378:metabolism*; D001710:Biotin / Q000096:biosynthesis* / Q000737:chemistry; D002244:Carbon / Q000737:chemistry; D018076:DNA, Complementary / Q000378:metabolism; D017353:Gene Deletion; D016681:Genome, Fungal; D018745:Genome, Plant; D005947:Glucose / Q000378:metabolism; D008856:Microscopy, Fluorescence / Q000379:methods; D008928:Mitochondria / Q000378:metabolism; D019301:Oleic Acid / Q000737:chemistry; D020675:Peroxisomes / Q000378:metabolism*
chemical_list: D000596:Amino Acids; D018076:DNA, Complementary; D019301:Oleic Acid; C001502:7-keto-8-aminopelargonic acid; D001710:Biotin; D002244:Carbon; D005947:Glucose