Structural analysis of the mitochondrial genome from the higher basidiomycete, Pleurotus ostreatus

高等担子菌的线粒体基因组(mt基因组)几乎没有关于整个基因组结构或基因结构和功能的分子遗传信息。本研究的目的是评估高等担子菌平菇线粒体基因组的总体结构，并阐明该真菌自然种群线粒体DNA限制性片段长度多态性(RFLP)的基础。在此基础上测定了该菌两种类型(菌株-5-17型和-286型)的mt基因组全序列。这两个mt基因组分别是71,948和72,466个碱基的环状分子，我观察到它们非常富含A+T(约73%)。通过使用BLAST和tRNA-Scan程序搜索517型mt基因组中的基因，总共鉴定出55个可能的基因。这些基因包括两种核糖体核糖核酸的基因，26个转移核糖核酸(TRNA)基因和14个功能已知蛋白质和…的开放阅读框架(ORF)有13个ORF被预测为可能的基因，不包括内含子ORF。平菇mt基因组的基因含量与已报道的其他真菌mt基因组的基因含量基本相同。Mt基因组中编码的tRNA基因数量不足以支持线粒体蛋白质的合成，这表明mt基因组中未检测到的tRNA基因可能是核编码的，并从细胞质输入。比较两个mt基因组结构，发现两个mt基因组在基因含量、基因顺序和每个基因的翻译方向等方面没有差异。然而，在比较两个mt基因组之间的序列差异时，发现了多个小片段的插入/缺失和点突变，主要发生在基因的间隔区，其中一些产生了新的限制性内切酶切点。此外，在基因间隔区和属内区也发现了长于1kb的插入/缺失大片段，其中存在不同的内含子序列。这特别表明，包含每个mt基因组的内含子序列的差异是在两者中观察到的RFLP产生的主要基础。较少

The mitochondrial genomes (mt-genomes) of the higher basidiomycetes have very little molecular genetic information regarding overall genome structure or gene structure and function. The aim of this study is to evaluate the overall structure of mt-genomes of the higher basidiomycete Pleurotus ostreatus and to clarify the basis for mitochondrial DNA restriction fragment length polymorphism (RFLP) in natural populations of this fungus. I thereupon determined the complete nucleotide sequence of two types (strain no.-5 17 type and -286 type) mt-genomes of this fungus. The two mt-genomes are 71,948 and 72,466 base pairs circular molecules and I observed that they are very A + T rich (about 73%). By searching for genes in the strain no. 517 type mt-genome using the programs BLAST and tRNA-scan, a total of 55 possible genes were identified. These included genes for two species of ribosomal RNA, 26 genes of transfer RNA (tRNA) and 14 open reading frames(ORFs) for functionally known proteins and … More 13 ORFs predicted as possible genes, excluding intronic ORFs. The gene content of P.ostreatus mt- genome is considered to be virtually the same as that of the other fungal mt- genomes that have been reported. The number of tRNA genes encoded in the mt- genome was not sufficient to support the synthesis of mitochondrial protein, suggesting that the undetectable tRNA genes in the mt-genome may be nuclear- encoded and imported from the cytoplasm. Comparing the two mt-genome structures, no differences were found between the two mt-genomes analyzed in terms of gene content, gene order and the direction for the translation of each gene. However, in a comparison of differences in sequence between the two mt- genomes, multiple small-size insertions/deletions and point mutations were found mainly in the interspacer region of genes, some of which produced new restriction sites. Moreover, large fragments of insertions/deletions longer than 1 kb were also found both in the interspacer regions of genes and in the intrageneric regions, where there were different intronic sequences. This indicates, in particular, that the difference of intronic sequences contained each mt-genome is the primary basis for the production of the RFLP observed in both. Less