Institut Pasteur, Unité de Génétique Moléculaire des Levures, CNRS UMR3525, Univ. P. M. Curie UFR927, Paris, France.
Genome Biol Evol. 2013;5(12):2524-39. doi: 10.1093/gbe/evt201.
The numerous yeast genome sequences presently available provide a rich source of information for functional as well as evolutionary genomics but unequally cover the large phylogenetic diversity of extant yeasts. We present here the complete sequence of the nuclear genome of the haploid-type strain of Kuraishia capsulata (CBS1993(T)), a nitrate-assimilating Saccharomycetales of uncertain taxonomy, isolated from tunnels of insect larvae underneath coniferous barks and characterized by its copious production of extracellular polysaccharides. The sequence is composed of seven scaffolds, one per chromosome, totaling 11.4 Mb and containing 6,029 protein-coding genes, ~13.5% of which being interrupted by introns. This GC-rich yeast genome (45.7%) appears phylogenetically related with the few other nitrate-assimilating yeasts sequenced so far, Ogataea polymorpha, O. parapolymorpha, and Dekkera bruxellensis, with which it shares a very reduced number of tRNA genes, a novel tRNA sparing strategy, and a common nitrate assimilation cluster, three specific features to this group of yeasts. Centromeres were recognized in GC-poor troughs of each scaffold. The strain bears MAT alpha genes at a single MAT locus and presents a significant degree of conservation with Saccharomyces cerevisiae genes, suggesting that it can perform sexual cycles in nature, although genes involved in meiosis were not all recognized. The complete absence of conservation of synteny between K. capsulata and any other yeast genome described so far, including the three other nitrate-assimilating species, validates the interest of this species for long-range evolutionary genomic studies among Saccharomycotina yeasts.
目前大量的酵母基因组序列为功能和进化基因组学提供了丰富的信息，但它们在很大程度上不能涵盖现存酵母的系统发育多样性。我们在这里介绍了 Kuraishia capsulata (CBS1993(T)) 单倍体型菌株的核基因组全序列，该菌株是一种从针叶树皮下昆虫幼虫隧道中分离出来的硝酸盐同化酿酒酵母目，其特征是大量产生细胞外多糖。该序列由七个支架组成，每个染色体一个，总长 11.4 Mb，包含 6029 个蛋白质编码基因，其中约 13.5%被内含子打断。这个 GC 丰富的酵母基因组（45.7%）在系统发育上与迄今为止测序的少数其他硝酸盐同化酵母，如 Ogataea polymorpha、O. parapolymorpha 和 Dekkera bruxellensis 有关，它们共享非常少的 tRNA 基因、一种新的 tRNA 节约策略和一个共同的硝酸盐同化簇，这是这个酵母群的三个特有特征。着丝粒在每个支架的 GC 贫乏槽中被识别。该菌株在单个 MAT 基因座上携带 MAT alpha 基因，与酿酒酵母基因具有高度的保守性，表明它可以在自然界中进行有性循环，尽管尚未识别出减数分裂相关基因。K. capsulata 与迄今为止描述的任何其他酵母基因组（包括其他三种硝酸盐同化物种）之间的基因排列完全没有保守性，这验证了该物种在酿酒酵母目中进行长距离进化基因组研究的重要性。
