30S ribosomal subunits with fragmented 16S RNA: a new approach for structure and function study of ribosomes.

A new approach for function and structure study of ribosomes based on oligodeoxyribonucleotide-directed cleavage of rRNA with RNase H and subsequent reconstitution of ribosomal subunits from fragmented RNA has been developed. The E coli 16S rRNA was cleaved at 9 regions belonging to different RNA domains. The deletion of 2 large regions was also produced by cleaving 16S rRNA in the presence of 2 or 3 oligonucleotides complementary to different RNA sites. Fragmented and deleted RNA were shown to be efficiently assembled with total ribosomal protein into 30S-like particles. The capacity to form 70S ribosomes and translate both synthetic and natural mRNA of 30S subunits reconstituted from intact and fragmented 16S mRNA was compared. All 30S subunits assembled with fragmented 16S rRNA revealed very different activity: the fragmentation of RNA at the 781-800 and 1392-1408 regions led to the complete inactivation of ribosomes, whereas the RNA fragmentation at the regions 296-305, 913-925, 990-998, 1043-1049, 1207-1215, 1499-1506, 1530-1539 did not significantly influence the ribosome protein synthesis activity, although it was also reduced. These findings are mainly in accordance with the data on the functional activity of some 16S rRNA sites obtained by other methods. The relations between different 16S RNA functional sites are discussed.