Doshi P, Bossie C A, Doonan J H, May G S, Morris N R
Department of Pharmacology, UMDNJ/Robert Wood Johnson Medical School, Piscataway 08854.
Mol Gen Genet. 1991 Jan;225(1):129-41. doi: 10.1007/BF00282651.
We have isolated and analyzed the tubA and tubB alpha-tubulin genes of Aspergillus nidulans. The nucleotide sequences of these genes predict polypeptides of 447 amino acids for tubA and 450 for tubB. The predicted amino acids sequences exhibit 28% divergence between the two polypeptides. This is the second known case of such high divergence between alpha-tubulins within the same species. The tubB gene is unique in that it codes for an extra glycine residue between what are usually the second and third amino acids. RNA blot analysis demonstrates that the tubA and tubB transcripts are each 1.8 kb long. The level of tubA transcript remains the same throughout the cell cycle. The level of tubB transcript does not change at any particular stage in the cell cycle but increases continuously during spore germination. The tubA gene was previously mapped to linkage group eight, and we have now mapped the tubB gene to linkage group four. Gene disruption in heterokaryons suggests that the phenotypic consequences of disruption are different for the tubA and tubB genes. Molecular disruption of tubA results in a block in nuclear division whereas in tubB it gives rise to abnormal cell and nuclear morphology.
我们已经分离并分析了构巢曲霉的tubA和tubBα-微管蛋白基因。这些基因的核苷酸序列预测tubA的多肽有447个氨基酸，tubB的多肽有450个氨基酸。预测的氨基酸序列显示这两种多肽之间有28%的差异。这是同一物种内α-微管蛋白之间出现如此高度差异的第二个已知案例。tubB基因的独特之处在于，它在通常的第二个和第三个氨基酸之间编码一个额外的甘氨酸残基。RNA印迹分析表明，tubA和tubB转录本均为1.8 kb长。tubA转录本的水平在整个细胞周期中保持不变。tubB转录本的水平在细胞周期的任何特定阶段都不会改变，但在孢子萌发过程中持续增加。tubA基因先前被定位到第八连锁群，我们现在已将tubB基因定位到第四连锁群。异核体中的基因破坏表明，tubA和tubB基因破坏的表型后果不同。tubA的分子破坏导致核分裂受阻，而tubB的破坏则导致细胞和核形态异常。
