J. Biol. Chem., Vol. 268, Issue 35, 26082-26084, Dec, 1993
Trp221 is involved in the protective effect of elongation factor eEF-2 on the ricin/alpha-sarcin site of the ribosome
D Guillot, JP Lavergne and JP Reboud
Laboratoire de Biochimie Medicale, Centre National de la Recherche Scientifique, Lyon, France.
Elongation factor eEF-2 treated by N-bromosuccinimide under conditions
which oxidize 2 Trp residues (Trp343 and Trp221) is inactivated in
ribosome-dependent GTP hydrolysis and polyphenylalanine synthesis, and
inactivation correlates with the specific oxidation of Trp221 (Guillot, D.,
Penin, F., Di Pietro, A., Sontag, B., Lavergne, J. P., and Reboud, J. P.
(1993) J. Biol. Chem. 268, 20911-20916). It is shown here that this
oxidation prevents neither GTP binding to eEF-2 nor the formation of the
ribosome-eEF-2-GPP(NH)P complex, but that oxidized eEF-2 is no longer able
to protect ribosomes against ricin inactivation. These observations suggest
that Trp221 or an amino-acid sequence containing this residue interacts
with the 28 S rRNA loop including the GAGA sequence, which is the target of
ricin. Such a hypothesis is discussed in relation with data on RNA
recognition motifs described in different proteins.