Nucleotide sequences of Escherichia coli 16-S RNA associated with ribosomal proteins S7, S9, S10, S14 and S19.

1. A ribonucleoprotein fragment containing proteins S7, S9, S10, S14, and S19 was isolated in high yield from Escherichia coli 30-S ribosomal sub-particles. The same fragment was obtained whether ribosomes from E. coli strain A19 or MRE 600 were used, despite the fact that protein S7 differs widely between the two strains. RNA was extracted from this fragment and fractionated on gels containing 7 M urea, to reveal "hidden breaks". A well-defined and reporducible pattern of RNA fragments was obtained, with the main components being approximately 300, 240, 130, 115 and 75 nucleotides in length, respectively. The pattern of RNA fragments obtained was also independent of the strain of E. coli used. 2. Two-dimensional fingerprints were made from ribonuclease T1 hydrolysates of these RNA fragments, labelled with 32P, and the oligonucleotides were further analysed by digestion with either ribonuclease A or U2. The data obtained were fitted in detail to the new 16-S RNA sequence map of Ehresmann et al. (1975). Again no significant differences were observed between the RNA from E. coli A19 or MRE 600. The RNA sequences found lay in the region O'-D-E'-K-P-P'-E-A of the 16-S RNA, with a clear excision of several nucleotides in section E'-K. The total sequence length covered was approximately 430 nucleotides.