Gold S E, Casale W L, Keen N T
Department of Plant Pathology, University of California, Riverside 92521.
Mol Gen Genet. 1991 Nov;230(1-2):104-12. doi: 10.1007/BF00290657.
The beta-tubulin genes G beta 1 and G beta 2 from the phytopathogenic hemiascomycete Geotrichum candidum were found to be highly diverged in amino acid sequence from those of other filamentous fungi. G beta 1 and G beta 2 were also divergent from each other, with the coding regions sharing only 66% nucleotide sequence homology and 64% amino acid identity. However, the proteins shared 82% similarity and only 25 of the 161 non-identical amino acid substitutions were non-conservative. The organization of G beta 1 is similar to other fungal beta-tubulin genes, but G beta 2 has several unusual features; it has 2 amino acid additions in the N-terminal 40 residues and must employ an uncommon 5' splice junction sequence in preference to an overlapping perfect consensus. The amino acid change found to confer benomyl resistance in Neurospora crassa was also present in G beta 2. G beta 1 has four introns which are located similarly to those of beta-tubulin genes in other fungi. G beta 2, however, has a single intron in a unique location. Translational fusions employing the 5' non-coding regions of the two Geotrichum beta-tubulin genes were made with the hygromycin phosphotransferase gene and shown to function in Schizosaccharomyces pombe and Trichoderma hamatum. However, G. candidum could not be transformed with these or other tested plasmids commonly used for fungal transformation.
人们发现，植物病原半子囊菌白地霉（Geotrichum candidum）的β-微管蛋白基因Gβ1和Gβ2在氨基酸序列上与其他丝状真菌的相应基因高度不同。Gβ1和Gβ2彼此之间也存在差异，其编码区的核苷酸序列同源性仅为66%，氨基酸同一性为64%。然而，这两种蛋白质的相似性为82%，在161个非同义氨基酸替换中，只有25个是非保守的。Gβ1的结构与其他真菌的β-微管蛋白基因相似，但Gβ2有几个不寻常的特征；它在N端的40个残基中有2个氨基酸添加，并且必须优先使用一个不常见的5'剪接连接序列，而不是一个重叠的完美共有序列。在粗糙脉孢菌（Neurospora crassa）中发现的赋予苯菌灵抗性的氨基酸变化在Gβ2中也存在。Gβ1有四个内含子，其位置与其他真菌的β-微管蛋白基因的内含子位置相似。然而，Gβ2在一个独特的位置有一个单一的内含子。利用白地霉两个β-微管蛋白基因的5'非编码区与潮霉素磷酸转移酶基因构建了翻译融合体，并证明其在粟酒裂殖酵母（Schizosaccharomyces pombe）和哈茨木霉（Trichoderma hamatum）中发挥作用。然而，白地霉不能用这些或其他常用于真菌转化的测试质粒进行转化。
