Maeder D L, Weiss R B, Dunn D M, Cherry J L, González J M, DiRuggiero J, Robb F T
The Center of Marine Biotechnology, University of Maryland Biotechnology Institute, Baltimore, Maryland 21202, USA.
Genetics. 1999 Aug;152(4):1299-305. doi: 10.1093/genetics/152.4.1299.
Divergence of the hyperthermophilic Archaea, Pyrococcus furiosus and Pyrococcus horikoshii, was assessed by analysis of complete genomic sequences of both species. The average nucleotide identity between the genomic sequences is 70-75% within ORFs. The P. furiosus genome (1.908 mbp) is 170 kbp larger than the P. horikoshii genome (1.738 mbp) and the latter displays significant deletions in coding regions, including the trp, his, aro, leu-ile-val, arg, pro, cys, thr, and mal operons. P. horikoshii is auxotrophic for tryptophan and histidine and is unable to utilize maltose, unlike P. furiosus. In addition, the genomes differ considerably in gene order, displaying displacements and inversions. Six allelic intein sites are common to both Pyrococcus genomes, and two intein insertions occur in each species and not the other. The bacteria-like methylated chemotaxis proteins form a functional group in P. horikoshii, but are absent in P. furiosus. Two paralogous families of ferredoxin oxidoreductases provide evidence of gene duplication preceding the divergence of the Pyrococcus species.
通过对嗜热古菌激烈火球菌（Pyrococcus furiosus）和堀越火球菌（Pyrococcus horikoshii）完整基因组序列的分析，评估了这两个物种的分化情况。两个基因组序列之间的开放阅读框（ORF）平均核苷酸同一性为70 - 75%。激烈火球菌的基因组（1.908兆碱基对）比堀越火球菌的基因组（1.738兆碱基对）大170千碱基对，并且后者在编码区域存在显著缺失，包括色氨酸、组氨酸、芳香族氨基酸、亮氨酸 - 异亮氨酸 - 缬氨酸、精氨酸、脯氨酸、半胱氨酸、苏氨酸和麦芽糖操纵子。与激烈火球菌不同，堀越火球菌对色氨酸和组氨酸营养缺陷，并且不能利用麦芽糖。此外，两个基因组在基因顺序上有很大差异，存在移位和倒位。两个火球菌基因组共有六个等位内含肽位点，每个物种都有两个内含肽插入，而另一个物种没有。类似细菌的甲基化趋化蛋白在堀越火球菌中形成一个功能组，但在激烈火球菌中不存在。铁氧化还原蛋白氧化还原酶的两个旁系同源家族为火球菌物种分化之前的基因复制提供了证据。
