Leucyl-tRNA synthetase from the extreme thermophile Aquifex aeolicus has a heterodimeric quaternary structure.
Class I aminoacyl-tRNA synthetases have been thought to be single polypeptide enzymes. However, the complete genome sequence of a hyper thermophile Aquifex aeolicus suggests that the gene for leucyl-tRNA synthetases (LeuRS) is probably split into two pieces (leuS and leuS'). In this research, each gene was separately cloned and overexpressed in Escherichia coli and the protein products were examined for LeuRS activity. Leucylation activity was detected only when both gene products coexisted. Gel filtration analysis showed that the active form of A. aeolicus LeuRS has a heterodimeric (alpha/beta type) quaternary structure that is unique among class I aminoacyl-tRNA synthetases.
Gouda
Masaki
M
Department of Biomolecular Science, Faculty of Engineering, Gifu University, Yanagido 1-1, 501-1193, Gifu, Japan.
Yokogawa
Takashi
T
Asahara
Haruichi
H
Nishikawa
Kazuya
K
D001419:Bacteria / Q000201:enzymology*; D003001:Cloning, Molecular; D019281:Dimerization; D004926:Escherichia coli / Q000235:genetics; D007700:Kinetics; D007930:Leucine / Q000378:metabolism; D007935:Leucine-tRNA Ligase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008954:Models, Biological; D020836:Protein Structure, Quaternary
D007935:Leucine-tRNA Ligase; D007930:Leucine