Peroxisomes Are Involved in Biotin Biosynthesis in Aspergillus and Arabidopsis
Peroxisomes Are Involved in Biotin Biosynthesis in Aspergillus and Arabidopsis
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DOI：
10.1074/jbc.m111.247338
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发表时间：
2011-09-02
影响因子：
4.8
通讯作者：
Kitamoto, Katsuhiko
中科院分区：
文献类型：
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作者：
Tanabe, Yasuko;Maruyama, Jun-ichi;Kitamoto, Katsuhiko
在真核生物中，只有植物和一些真菌能够合成生物素。虽然导致生物素生物合成的初始事件在很大程度上仍然未知，但已知最终步骤发生在线粒体中。在这里，我们删除了丝状真菌米曲霉中分别编码过氧化物酶体靶向信号PTS 1和PTS 2受体的Aopex 5和Aopex 7基因。除了在PTS 1或PTS 2蛋白的过氧化物酶体靶向中表现出缺陷之外，缺失菌株还在含有油酸作为唯一碳源的基本培养基上表现出生长缺陷。出乎意料的是，这些过氧化物酶体转运缺陷型菌株在含有葡萄糖作为唯一碳源的基本培养基上也表现出生长缺陷，通过添加生物素及其前体（包括7-酮基-8-氨基壬酸（KAPA））来补救。在真菌和植物基因组数据库中搜索发现，生物素生物合成酶之一BioF蛋白/KAPA合酶在C末端具有PTS 1序列。表达缺乏PTS 1的真菌和植物BioF蛋白的真菌Delta bioF菌株在不存在生物素的情况下仍表现出生长缺陷，表明过氧化物酶体靶向KAPA合酶对于生物素生物合成至关重要。此外，在植物拟南芥中，AtBioF通过识别其PTS 1序列定位于过氧化物酶体，表明过氧化物酶体参与植物中的生物素生物合成。两者合计，我们证明了过氧化物酶体在生物素生物合成中的一个新的作用，并建议存在尚未确定的过氧化物酶体蛋白，在生物素生物合成的早期步骤中发挥作用。
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 Delta bioF 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.