Connerton I F, Fincham J R, Sandeman R A, Hynes M J
Department of Genetics, University of Cambridge, UK.
Mol Microbiol. 1990 Mar;4(3):451-60. doi: 10.1111/j.1365-2958.1990.tb00611.x.
The genes encoding the acetate-inducible enzyme acetyl-coenzyme A synthetase from Neurospora crassa and Aspergillus nidulans (acu-5 and facA, respectively) have been cloned and their sequences compared. The predicted amino acid sequence of the Aspergillus enzyme has 670 amino acid residues and that of the Neurospora enzyme either 626 or 606 residues, depending upon which of the two possible initiation codons is used. The amino acid sequences following the second alternative AUG show 86% homology between the two species; the extended N-terminal sequences show no homology. The Neurospora protein is characterized by the appearance of the S(T)PXX sequence motif where the amino acid homologies break down. The codon usage is biased in both genes, with a marked deficiency, especially in Neurospora, of codons with A in the third position. The facA transcribed sequence contains six introns: one in the long leader sequence, one in the 5' coding sequence not homologous with acu-5, and four within the sequence that is largely similar to that of acu-5. Only one intron, corresponding in size and position to the furthest downstream of the facA introns, is found in acu-5. The evolution of introns during the divergence of these two Ascomycete fungi is discussed. Each of the two genes has been transferred by transformation into the other species. Each species is evidently able to splice out the other's introns. Most transformants have normal acetate-induction of acetyl-CoA synthetase, implying that the two genes respond to transcriptional control signals common to both species, in spite of the striking divergence of their 5' ends.
已克隆了分别来自粗糙脉孢菌和构巢曲霉的编码乙酸盐诱导型酶乙酰辅酶A合成酶的基因（分别为acu - 5和facA），并对它们的序列进行了比较。构巢曲霉该酶的预测氨基酸序列有670个氨基酸残基，粗糙脉孢菌该酶的预测氨基酸序列根据所使用的两个可能起始密码子中的哪一个，有626个或606个残基。在第二个替代AUG之后的氨基酸序列在这两个物种之间显示出86%的同源性；延伸的N端序列没有同源性。粗糙脉孢菌的蛋白质以氨基酸同源性中断处出现的S(T)PXX序列基序为特征。这两个基因的密码子使用都有偏向性，尤其是在粗糙脉孢菌中，第三位为A的密码子明显缺乏。facA转录序列包含六个内含子：一个在长前导序列中，一个在与acu - 5不同源的5'编码序列中，还有四个在与acu - 5序列基本相似的序列内。在acu - 5中仅发现一个内含子，其大小和位置与facA内含子最下游的内含子相对应。讨论了这两种子囊菌在分化过程中内含子的进化。这两个基因中的每一个都已通过转化转移到另一个物种中。每个物种显然都能够剪接出另一个物种的内含子。大多数转化体对乙酰辅酶A合成酶有正常的乙酸盐诱导作用，这意味着尽管它们5'端有显著差异，但这两个基因对两个物种共有的转录控制信号有反应。
