Binding of adenosine 3':5'-cyclic phosphate to G factor of Escherichia coli, and its effects on GTPase, RNase V, and protein synthesis.

Unique among adenine nucleotides tested by filter binding assays, 3':5'-cyclic AMP binds to the G translocation factor. Binding is dependent on the presence of GTP, and is inhibited by GDP, by the analog 5'-beta,gamma-methylene GTP, and by the antibiotic fusidic acid. The cAMP seems to be released during the ribosome-dependent translocation of charged tRNA catalyzed by G factor. Bound cAMP inhibits GTPase and ribosome-associated degradation of messenger RNA, but does not inhibit protein synthesis. cAMP might thereby regulate the ratio of productive to degradative transits of ribosomes on messenger RNA, and this may account for some part of its profound effect on levels of specific bacterial messenger RNA species.