Interactions of periodate-oxidized guanine nucleotides with

GUANINE

NUCLEOTIDES A N D EF-G

Interactions of Periodate-Oxidized Guanine Nucleotides with Escherichia coli Elongation Factor G and the Ribosome+ James W. Bodley and Julian Gordon*

ABSTRACT:

Both periodate-oxidized G D P (GDPoX) and its KBH4-reduction product (GDPoX-red)bind to the ribosome and EF-G in the presence of fusidic acid. The complexes formed with these two nucleotides are only slightly less stable than that with G D P itself. However, the binding of both GDPoX and G D P x - r e d as observed by Millipore filtration is more dependent on the presence of fusidic acid than is the binding of GDP. A similar pattern of binding was observed with the analogous nucleotides derived from G T P (GTPOXand GTPOX-'ed) except that the y-phosphate was released on binding. However, in the usual catalytic hydrolysis reaction performed in the absence of fusidic acid, both GTPoXand GTPoX-redwere poor substrates with rates of hydrolysis