Ogihara Fukashi, Kitagaki Hiroshi, Wang Qian, Shimoi Hitoshi
Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, 1-3-1 Kagamiyama, Higashihiroshima 739-8530, Japan.
Yeast. 2008 Jun;25(6):419-32. doi: 10.1002/yea.1596.
Genomic analysis of industrial yeast strains is important for exploitation of their potential. We analysed the genomic structure of the most widely used sake yeast strain, Kyokai no. 7 (K7), by DNA microarray. Since the analysis suggested that the copy number of the AQY1-ARR3 region in the right arm of chromosome XVI was amplified, we performed Southern blot analysis using the AQY1 gene as a probe. The probe hybridized to three bands in the widely used sake strains derived from K7, but only to one band of 1.4 kb in the laboratory strains. Since the extra two bands were not observed in old sake strains, or in other industrial strains, the amplification of this region appeared to be specific for the widely used sake strains. The copy number of the AQY1-ARR3 region appeared to have increased by chromosomal translocation, since chromosomal Southern blot analysis revealed that the AQY1 probe hybridized to chromosomes IV and XIII, in addition to chromosome XVI, in which AQY1 of the laboratory strain is encoded. The chromosomal translocation was also confirmed by PCR analysis using primers that amplify the region containing the breakpoint. Cloning and sequencing of cosmids that encode the AQY1-ARR3 region revealed that this region is flanked by TG(1-3) repeats on the centromere-proximal side in chromosomes IV and XIII, suggesting that amplification of this region occurred by homologous recombination through TG(1-3) repeats. These results demonstrate the genomic characteristics of the modern widely used sake strains that discriminate them from other strains.
对工业酵母菌株进行基因组分析对于挖掘其潜力至关重要。我们通过DNA微阵列分析了应用最广泛的清酒酵母菌株——日本酿造研究所7号（K7）的基因组结构。由于分析表明第十六条染色体右臂上的AQY1 - ARR3区域的拷贝数被扩增，我们以AQY1基因作为探针进行了Southern印迹分析。该探针在源自K7的广泛应用的清酒菌株中与三条带杂交，但在实验室菌株中仅与一条1.4 kb的带杂交。由于在陈旧的清酒菌株或其他工业菌株中未观察到另外两条带，该区域的扩增似乎是广泛应用的清酒菌株所特有的。AQY1 - ARR3区域的拷贝数似乎是通过染色体易位增加的，因为染色体Southern印迹分析显示，除了实验室菌株中编码AQY1的第十六条染色体外，AQY1探针还与第四条和第十三条染色体杂交。使用扩增包含断点区域的引物进行PCR分析也证实了染色体易位。对编码AQY1 - ARR3区域的黏粒进行克隆和测序表明，该区域在第四条和第十三条染色体着丝粒近端一侧侧翼为TG(1 - 3)重复序列，这表明该区域的扩增是通过TG(1 - 3)重复序列的同源重组发生的。这些结果证明了现代广泛应用的清酒菌株区别于其他菌株的基因组特征。
