Mitochondrial tRNATrps
Imply a Eubacterial Origin
CHEN Li, JIN You-Xin, WANG De-Bao
( State Key Laboratory of Molecular Biology, Shanghai Institute of
Biochemistry,the Chinese Academy of Sciences, Shanghai 200031, China
)
Abstract Three
mitochondrial tRNATrps genes from Oryza sativa, Homo
sapiens and Saccharomyces serevisea were constructed. In
vitro transcripts of these mitochondrial tRNATrps genes were
able to be tryptophanylated by Bacillus subtilis tryptophanyl-tRNA
synthetase (TrpRS), but could not be catalyzed by TrpRS from rat liver. Kinetic
assay showed that B. subtilis TrpRS had half the binding capacity for
mitochondrial tRNATrps than for wild type tRNATrp. While
in the catalytic efficiency, the kcat/Km value
of mitochondrial tRNATrps from O.sativa and S.serevisea
by B.subtilis enzyme was reduced by 400-fold and 1 200-fold
respectively as that of B.subtilis tRNATrp. Experimental
results suggested that mitochondrial tRNATrps implied a eubacterial
origin.
Key words mitochondrial tRNATrp； acceptor stem； discriminator base； origin
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