THE E35 STOPPER MUTANT OF NEUROSPORA-CRASSA - PRECISE LOCALIZATION OF DELETION END-POINTS IN MITOCHONDRIAL-DNA AND EVIDENCE THAT THE DELETED DNA CODES FOR A SUBUNIT OF NADH DEHYDROGENASE
THE E35 STOPPER MUTANT OF NEUROSPORA-CRASSA - PRECISE LOCALIZATION OF DELETION END-POINTS IN MITOCHONDRIAL-DNA AND EVIDENCE THAT THE DELETED DNA CODES FOR A SUBUNIT OF NADH DEHYDROGENASE
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DOI：
10.1002/j.1460-2075.1986.tb04281.x
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发表时间：
1986-04-01
期刊：
影响因子：
11.4
通讯作者：
RAJBHANDARY, UL
中科院分区：
文献类型：
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作者：
DEVRIES, H;ALZNERDEWEERD, B;RAJBHANDARY, UL
粗枝脉孢菌的塞子突变体E35中发现了两种大缺失的线粒体DNA分子(5KBP和40KBP)。跨越缺失终点的连接片段现在已经被克隆和测序，并将它们的序列与相应的野生型片段的序列进行比较。我们发现，这两种类型的线粒体DNA缺陷都是由短直接重复序列的缺失引起的，短直接重复序列本身就是更大的反向重复序列的一部分。在每种情况下，短的直接重复序列都由一条链中的一串嘧啶和另一条链中的嘌呤组成。我们还报道了一个2151个碱基的HindIII片段的序列，该片段在两个有缺陷的线粒体DNA中都缺失了。除了先前发现的蛋氨酸tRNA基因外，2151个碱基的DNA序列还包含一个开放阅读框，有可能编码一个583个氨基酸长的疏水蛋白。这种疏水蛋白与其他线粒体基因组中发现的URF2编码的蛋白有三个显著的同源性。由于哺乳动物线粒体URF2最近被发现编码NADH脱氢酶的一个亚基，因此粗枝线虫E35阻断突变体中缺失的DNA序列的一部分也可能编码NADH脱氢酶的一个亚基。
Two types of defective mitochondrial DNA molecules with large deletions (5 kbp and 40 kbp) have previously been identified in the stopper mutant, E35, of Neurospora crassa. The junction fragments spanning the deletion endpoints have now been cloned and sequenced, and their sequences compared with those of the corresponding wild‐type fragments. We show that both types of defective mitochondrial DNAs result from deletions of sequences flanked by short direct repeats, which are themselves parts of larger inverted repeat sequences. In every case, the short direct repeat sequences consist of a run of pyrimidines in one strand and purines in the other. We also report the sequence of a 2151‐bp HindIII fragment, which is deleted in both of the defective mitochondrial DNAs. Besides the previously identified gene for a methionine tRNA, the 2151‐bp DNA sequence contains an open reading frame with the potential to code for a hydrophobic protein 583 amino acids long. This hydrophobic protein has three blocks of significant homology with proteins coded by URF2 found in other mitochondrial genomes. Since the mammalian mitochondrial URF2 has recently been shown to code for a subunit of NADH dehydrogenase, part of the DNA sequence missing in the E35 stopper mutant of N. crassa may also code for a subunit of NADH dehydrogenase.