Selective chemical modification of Escherichia coli elongation factor G. N-Ethylmaleimide modification of a cysteine essential for nucleotide binding.
1976; Elsevier BV; Volume: 251; Issue: 4 Linguagem: Inglês
10.1016/s0021-9258(17)33782-1
ISSN1083-351X
AutoresMichael S. Rohrbach, James W. Bodley,
Tópico(s)DNA and Nucleic Acid Chemistry
ResumoEscherichia coli Elongation Factor G is inhibited ireversibly by the chemical modification of 1 cysteine residue with N-ethylmaleimide. At pH 5.2, this cysteine is approximately 130 times more reactive than beta-mercaptoethanol toward N-ethylmaleimide. Inhibition is not prevented by either the ribosome or GTP alone at concentrations approximately equal to that of Elongation Factor G, but in combination they reduce the inhibition by 50%. Increasing the stability of the Elongation Factor G-ribosome-GDP complex by the addition of fusidec acid, completely protects against N-ethylmaleimide inhibition. The modified protein cannot form either the Elongation Factor G-ribosome-GMP-P(CH2)P or the Elongation Factor G-ribosome-GDP-fusidic acidcomplex. However, the modification had no effect on its ability to form the Elongation Factor G-ribosome complex. These results suggest that the cysteine residue modified by N-ethylmaleimide is at or near the nucleotide binding site.
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