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）在总体基因组结构或基因结构和功能方面的分子遗传信息很少。本研究的目的是评估高等担子菌平菇（Pleurotus ostreatus） mt-基因组的整体结构，并阐明该真菌自然群体线粒体DNA限制性片段长度多态性（RFLP）的基础。因此，我确定了两种类型（株）的完整核苷酸序列。-5 17型和-286型)mt-基因组。两个mt-基因组分别是71,948和72,466个碱基对圆形分子，我观察到它们非常富含A + T（约73%）。通过寻找no.菌株的基因。利用BLAST和trna扫描程序，共鉴定出55个可能的基因。这些基因包括两种核糖体RNA的基因，26个转移RNA （tRNA）基因和14个功能已知蛋白质的开放阅读框（orf）基因，其中13个orf被预测为可能的基因，不包括内含子orf。postreatus mt-基因组的基因含量被认为与其他已报道的真菌mt-基因组几乎相同。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，并从细胞质中输入。比较两种mt-基因组的结构，发现两种mt-基因组在基因含量、基因顺序和每个基因的翻译方向上没有差异。然而，在比较两个mt-基因组序列的差异时，发现多个小尺寸的插入/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位点。此外，在基因间隔区和不同内含子序列的基因内区域也发现了长度大于1 kb的插入/缺失大片段。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。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