Colocalization of Amanitin and a Candidate Toxin-Processing Prolyl Oligopeptidase in Amanita Basidiocarps
Colocalization of Amanitin and a Candidate Toxin-Processing Prolyl Oligopeptidase in Amanita Basidiocarps
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DOI：
10.1128/ec.00161-10
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发表时间：
2010-12-01
期刊：
影响因子：
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通讯作者：
Walton, Jonathan D.
中科院分区：
文献类型：
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作者：
Luo, Hong;Hallen-Adams, Heather E.;Walton, Jonathan D.
担子菌属的Amanita真菌具有很高的哺乳动物毒性，这是由于α -amanitin等双环八肽amamitoxins引起的。Amatoxins和相关的phalloidin（如七肽phalloidin）由MSDIN基因家族成员编码，并在核糖体上合成为短（34- 35个氨基酸）原蛋白。用抗amanitin抗体和共聚焦显微镜测定了北美东部毁灭天使（Amanita bisporigera）担子果（蘑菇）中amanitin积累的细胞和亚细胞定位。与先前的研究一致，amamantin存在于整个担子果皮（柄、毛、片层、瘤和总膜），但它只存在于这些组织中的一小部分细胞中。某些细胞对amantin的限制在膜中特别明显。一些证据表明，一种特殊的脯氨酰寡肽酶a . bisporigera POPB （AbPOPB）在amantin和phallotoxin原蛋白的初始加工过程中起作用。AbPOPB基因在分类上局限于产蛋黄素的金刚鹦鹉属物种，并聚集在基因组中，至少有一个表达的MSDIN基因家族成员。在免疫学上，amanitin和AbPOPB表现出高度的共定位，表明毒素的生物合成和积累发生在相同的细胞中，可能发生在相同的亚细胞区室中。
Fungi in the basidiomycetous genus Amanita owe their high mammalian toxicity to the bicyclic octapeptide amatoxins such as alpha-amanitin. Amatoxins and the related phallotoxins (such as the heptapeptide phalloidin) are encoded by members of the "MSDIN" gene family and are synthesized on ribosomes as short (34- to 35-amino-acid) proproteins. Antiamanitin antibodies and confocal microscopy were used to determine the cellular and subcellular localizations of amanitin accumulation in basidiocarps (mushrooms) of the Eastern North American destroying angel (Amanita bisporigera). Consistent with previous studies, amanitin is present throughout the basidiocarp (stipe, pileus, lamellae, trama, and universal veil), but it is present in only a subset of cells within these tissues. Restriction of amanitin to certain cells is especially marked in the hymenium. Several lines of evidence implicate a specific prolyl oligopeptidase, A. bisporigera POPB (AbPOPB), in the initial processing of the amanitin and phallotoxin proproteins. The gene for AbPOPB is restricted taxonomically to the amatoxin-producing species of Amanita and is clustered in the genome with at least one expressed member of the MSDIN gene family. Immunologically, amanitin and AbPOPB show a high degree of colocalization, indicating that toxin biosynthesis and accumulation occur in the same cells and possibly in the same subcellular compartments.