Structure and function of nucleic acids affected by high pressure

Abstract

Recently we have shown that oligodeoxynucleotides and oligoribonucleotides change their conformation at high pressure from B to Z and from A to Z respectively [Krzyzaniak et al. 1991, 1994a]. Now we are interested what is the effect of pressure on the native RNA. The structure of transfer ribonucleic acids (tRNA) and ribosomal 5S RNA undergo small conformational changes at high pressure. The changes were studied by circular dichroism (CD) but difficult to identify precisely. At high pressure conditions (6 kbar) Escherichia coli phenylalanine specific tRNA Ph~ can be aminoacylated (charged) specifically with amino acid, in absence of the specific aminoacyl tRNA synthetases and ATP [Krzyzaniak et al. 1994b]. We found that the esterification reaction at high pressure, similarly to the enzymatic one, occured at the 3'-end of the tRNA molecules. It seems plausible that a conformation oftRNA induced by the aminoacyl tRNA synthetase during enzymatic aminoacylation and that one induced at high pressure are very similar or identical. We think that the "unique" tertiary structure of tRNA creates an active centre where ester bond is formed. If so, it is obvious that a structure of the amino acid stem of tRNA determines specificity of specific tRNA with amino acid. The product of the aminoacylation reaction at high pressure, PhetRNA Phe was as good substrate as that one obtained enzymatically for in vitro polyphenylalanine synthesis in the presence of poly U. We have also shown that high pressure can catalyse elongation of short peptides. These observations have some relevance to the origin of protein synthesis. On the early stages of evolution (RNA world), RNA molecule played dual role. It could function as an enzyme and information carrier. For this reaction aminoacyl-tRNA is used as an amino acid donor. This paper and our current work strongly supports that RNA dependent amino