title: tRNA and the guanosinetriphosphatase activity of elongation factor Tu.
abstract: Different sites of the tRNA molecule influence the activity of the elongation factor Tu (EF-Tu) center for GTP hydrolysis [Parlato, G., Pizzano, R., Picone, D., Guesnet, J., Fasano, O., & Parmeggiani, A. (1983) J. Biol. Chem. 258, 995-1000]. Continuing these studies, we have investigated some aspects of (a) the effect of different tRNA(Phe) species, including Ac-Phe-tRNA(Phe) and 3'-truncated tRNA-CCA in the presence and absence of codon-anticodon interaction, and (b) the effect of occupation of the ribosomal P-site by different tRNA(Phe) species. Surprisingly, we have found that 3'-truncated tRNA can enhance the GTPase activity in the presence of poly(U), in contrast to its inhibitory effect in the absence of codon-anticodon interaction. Moreover, Ac-Phe-tRNA(Phe) was found to have some stimulatory effect on the ribosome EF-Tu GTPase in the presence of poly(U). These results indicate that under specific conditions the 3'-terminal end and a free terminal alpha-NH2 group are not essential for the stimulation of the catalytic center of EF-Tu; therefore, the same structure of the tRNA molecule can act as a stimulator or an inhibitor of EF-Tu functions, depending on the presence of codon-anticodon interaction and on the concentration of monovalent and divalent cations. EF-Tu-GTP does not recognize a free ribosomal P-site from a P-site occupied by the different tRNA(Phe) species. When EF-Tu acts as a component of the ternary complex formed with GTP and aa-tRNA, the presence of tRNA in the P-site strongly increases the GTPase activity.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Laboratoire de Biochimie, Ecole Polytechnique, Palaiseau, France.
authors.forename: G W
authors.initials: GW
authors.lastname: Swart
authors.forename: A
authors.initials: A
authors.lastname: Parmeggiani
mesh_terms: D000926:Anticodon / Q000378:metabolism; D001665:Binding Sites; D003062:Codon / Q000378:metabolism; D020963:GTP Phosphohydrolase-Linked Elongation Factors / Q000378:metabolism*; D006868:Hydrolysis; D007700:Kinetics; D010444:Peptide Elongation Factor Tu / Q000378:metabolism*; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism*; D011072:Poly U / Q000378:metabolism; D012345:RNA, Transfer, Amino Acid-Specific / Q000378:metabolism*; D012346:RNA, Transfer, Amino Acyl / Q000378:metabolism; D012360:RNA, Transfer, Phe / Q000378:metabolism*; D012270:Ribosomes / Q000378:metabolism
chemical_list: D000926:Anticodon; D003062:Codon; D012345:RNA, Transfer, Amino Acid-Specific; D012346:RNA, Transfer, Amino Acyl; D012360:RNA, Transfer, Phe; C006383:tRNA, N-acetylphenylalanine-; D011072:Poly U; D010744:Phosphoric Monoester Hydrolases; D020963:GTP Phosphohydrolase-Linked Elongation Factors; D010444:Peptide Elongation Factor Tu