Cue D, Beckler G S, Reeve J N, Konisky J
Proc Natl Acad Sci U S A. 1985 Jun;82(12):4207-11. doi: 10.1073/pnas.82.12.4207.
The DNA sequences of a region that includes the hisA gene of two related methanogenic archaebacteria, Methanococcus voltae and Methanococcus vannielii, have been compared. Both organisms show a similar genome organization in this region, displaying three open reading frames (ORFs) separated by regions of very high A + T content. Two of the ORFs, including ORFHisA, show significant DNA sequence homology. As might be expected for organisms having a genome that is A + T-rich, there is a high preference for A and U as the third base in codons. Although the regions upstream of the structural genes contain prokaryotic-like promoter sequences, it is not known whether they are recognized as promoters in these archaebacterial cells. A ribosome binding site, G-G-T-G, is located 6 base pairs preceding the ATG translation initiation sequence of both hisA genes. The sequences upstream of the two hisA genes show only limited sequence homology. The M. voltae intergenic region contains four tandemly arranged repetitions of an 11-base-pair sequence, whereas the M. vannielii sequence contains both direct and inverted repetitive sequences. Based on the degree of hisA sequence homology, we conclude that M. voltae and M. vannielii are less closely related taxonomically than are members of the enteric group of eubacteria.
对包括两种相关产甲烷古细菌沃氏甲烷球菌（Methanococcus voltae）和万氏甲烷球菌（Methanococcus vannielii）的hisA基因在内的一个区域的DNA序列进行了比较。两种生物在该区域显示出相似的基因组组织，呈现出三个开放阅读框（ORF），由A+T含量非常高的区域隔开。其中两个ORF，包括ORFHisA，显示出显著的DNA序列同源性。正如富含A+T基因组的生物所预期的那样，密码子的第三个碱基对A和U有高度偏好。尽管结构基因上游的区域含有类似原核生物的启动子序列，但尚不清楚它们在这些古细菌细胞中是否被识别为启动子。核糖体结合位点G-G-T-G位于两个hisA基因的ATG翻译起始序列之前6个碱基对处。两个hisA基因上游的序列仅显示出有限的序列同源性。沃氏甲烷球菌的基因间区域包含一个11碱基对序列的四个串联重复，而万氏甲烷球菌的序列包含正向和反向重复序列。基于hisA序列同源性的程度，我们得出结论，沃氏甲烷球菌和万氏甲烷球菌在分类学上的亲缘关系比真细菌肠道菌群的成员要远。
