Document Type

Article

Publication Date

7-7-2000

Abstract

Elongation factor (EF) Tu promotes the binding of aminoacyl-tRNA (aa-tRNA) to the acceptor site of the ribosome. This process requires the formation of a ternary complex (EF-Tu·GTP·aa-tRNA). EF-Tu is released from the ribosome as an EF-Tu·GDP complex. Exchange of GDP for GTP is carried out through the formation of a complex with EF-Ts (EF-Tu·Ts). Mammalian mitochondrial EF-Tu (EF-Tumt) differs from the corresponding prokaryotic factors in having a much lower affinity for guanine nucleotides. To further understand the EF-Tumt subcycle, the dissociation constants for the release of aa-tRNA from the ternary complex (K tRNA) and for the dissociation of the EF-Tu·Tsmt complex (K Ts) were investigated. The equilibrium dissociation constant for the ternary complex was 18 ± 4 nM, which is close to that observed in the prokaryotic system. The kinetic dissociation rate constant for the ternary complex was 7.3 × 10 4 s 1, which is essentially equivalent to that observed for the ternary complex inEscherichia coli. The binding of EF-Tumt to EF-Tsmt is mutually exclusive with the formation of the ternary complex. K Ts was determined by quantifying the effects of increasing concentrations of EF-Tsmt on the amount of ternary complex formed with EF-Tumt. The value obtained for K Ts(5.5 ± 1.3 nM) is comparable to the value ofK tRNA.

Comments

© 2000 American Society for Biochemistry and Molecular Biology Inc. Original published version available at http://doi.org/10.1074/jbc.M001899200.

Cai, Y., Bullard, J., Thompson, R., et al. Interaction of Mitochondrial Elongation Factor Tu With Aminoacyl-tRNA and Elongation Factor Ts. Journal of Biological Chemistry 2000, vol. 275, 20308-20314.

First Page

20308

Last Page

20314

Publication Title

Journal of Biological Chemistry

DOI

10.1074/jbc.M001899200

Included in

Chemistry Commons

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