Search for primitive Methanopyrus based on genetic distance between Val- and Ile-tRNA synthetases.
Since evidence indicates that the Last Universal Common Ancestor (LUCA) was phylogenetically closest to Methanopyrus kandleri among living organisms with elucidated genomes, this study has been directed to a search for the most primitive Methanopyrus lineage. For this purpose, the divergence of valyl-tRNA synthetase (ValRS) and isoleucyl-tRNA synthetase (IleRS) was employed as a measure of primitivity. Comparison of Methanopyrus kandleri and the Methanopyrus isolates GC34 and GC37 from the Pacific Ocean and KOL6, TAG1, TAG11, and SNP6 from the Atlantic Ocean established that the Pacific lineages are more primitive than the Atlantic lineages. Both the groups, however, are younger than environmental genomes from the Kairei Field of Central Indian Ridge in the Indian Ocean. These results showed that different Methanopyrus isolates differ significantly with respect to ValRS-IleRS divergence. On this basis, genomes giving rise to the ValRS and IleRS gene fragments from the Central Indian Ridge represent the most primitive Methanopyrus, phylogenetically the oldest living lineage closest to LUCA.
Yu
Zhiliang
Z
Department of Biochemistry, Fok Ying Tung Graduate School, Applied Genomics Center, Hong Kong University of Science and Technology, Hong Kong, China.
Takai
Ken
K
Slesarev
Alexei
A
Xue
Hong
H
Wong
J Tze-Fei
JT
D001105:Archaea / Q000201:enzymology* / Q000235:genetics*; D001267:Atlantic Ocean; D001483:Base Sequence; D002999:Clone Cells; D004275:DNA, Ribosomal / Q000235:genetics; D014644:Genetic Variation; D019156:Indian Ocean; D007533:Isoleucine-tRNA Ligase / Q000235:genetics*; D008969:Molecular Sequence Data; D010140:Pacific Ocean; D012689:Sequence Homology, Nucleic Acid; D014637:Valine-tRNA Ligase / Q000235:genetics*
D004275:DNA, Ribosomal; D007533:Isoleucine-tRNA Ligase; D014637:Valine-tRNA Ligase