title: Binding of eucaryotic elongation factor Tu to nucleic acids.
abstract: The binding of eucaryotic elongation factor Tu (eEF-Tu) to nucleic acids was investigated. eEF-Tu binds to a variety of different nucleic acids with high affinity, showing a strong preference for 18 S and 28 S rRNA over transfer RNA and for ribose-containing polymers over polydeoxyribonucleotides. The factor binds at multiple sites on 28 S rRNA without strong cooperativity. eEF-Tu binds strongly to poly(G) and poly(U) but weakly, if at all, to poly(A) and poly(C). Experiments employing an airfuge demonstrate that eEF-Tu can form a quaternary complex containing the factor, 28 S rRNA, aminoacyl-tRNA, and GTP. The existence of two distinct RNA binding sites on eEF-Tu suggests that rRNA may play a role in the recognition of eEF-Tu.aminoacyl-tRNA.GTP complexes by polysomes. Support for this suggestion comes from experiments which show that poly(G) inhibits the factor-dependent binding of aminoacyl-tRNA to mRNA-programmed 80 S ribosomes. In addition, it is shown that eEF-Tu possesses an intrinsic GTPase activity which is stimulated significantly by 28 S rRNA, poly(G), and poly(U). The binding of eEF-Tu to poly(G) lowers the activation energy for eEF-Tu GTPase from 74.3 to 65.9 kJ . mol-1 and approximately doubles the Vmax of the enzymatic reaction. The results are discussed in relation to the binding of eEF-Tu to ribosomes during protein synthesis.
mesh_terms: D004926:Escherichia coli; D006160:Guanosine Triphosphate / Q000378:metabolism; D046911:Macromolecular Substances; D010444:Peptide Elongation Factor Tu; D010445:Peptide Elongation Factors / Q000378:metabolism*; D011068:Poly G / Q000378:metabolism; D011072:Poly U / Q000378:metabolism; D012313:RNA / Q000378:metabolism*; D012335:RNA, Ribosomal / Q000378:metabolism; D012343:RNA, Transfer / Q000378:metabolism; D012346:RNA, Transfer, Amino Acyl / Q000378:metabolism
chemical_list: D046911:Macromolecular Substances; D010445:Peptide Elongation Factors; D012335:RNA, Ribosomal; D012346:RNA, Transfer, Amino Acyl; D011068:Poly G; D011072:Poly U; D012313:RNA; D006160:Guanosine Triphosphate; D012343:RNA, Transfer; D010444:Peptide Elongation Factor Tu