Cooperativity in low-affinity Mg2+ binding to tRNA.
The Pb2+-catalyzed cleavage of tRNAPhe has been used to probe the effect of Na+ and Mg2+ binding to tRNA. Na+ is a noncompetitive inhibitor of the Pb2+-catalyzed cleavage. Millimolar Mg2+ is also a noncompetitive inhibitor. Analysis of the Mg2+ data show that at least two sites are involved in binding and that there is an interaction between the sites (cooperativity). Low-affinity Mg2+ binding is thus different from "weak" and "strong" Mg2+ binding to tRNA characterized previously. We postulate that the alterations induced by low-affinity Mg2+ binding in tRNA mimic to some extent those brought about in RNA by the interaction with a protein factor and that at appropriate [Mg2+] the whole structure of tRNA is able to respond in a concerted way to a signal from the environment such as aminoacylation or codon binding.
D001665:Binding Sites; D003461:Crystallography; D006868:Hydrolysis; D007854:Lead / Q000494:pharmacology; D008274:Magnesium / Q000378:metabolism*; D008433:Mathematics; D012343:RNA, Transfer / Q000378:metabolism*; D012346:RNA, Transfer, Amino Acyl / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D015003:Yeasts
D012346:RNA, Transfer, Amino Acyl; D007854:Lead; D012343:RNA, Transfer; D012964:Sodium; D008274:Magnesium