Nucleotide sequence analysis of precursor 5S RNA from Bacillus licheniformis.

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RESUMO

The complete nucleotide sequences of the various precursor 5S RNA species occurring in Bacillus licheniformis have been elucidated. The B. licheniformis precursors contain a 5'-precursor-specific segment of 95 nucleotides which is four times as long as the corresponding segment of the p5S RNAs from the closely related strains B. subtilis (Sogin, M.L., Pace, N.R., Rosenberg, M., Weissman, S.M. (1976) J. Biol. Chem. 251, 3480-3488) and Bacillus Q (Stiekema, W.J., Raué, H.A., Planta, R.J. (1980) Nucl. Ac. Res. 8, 2193-2211). However, fourteen of the sixteen nucleotides at the 5'-end are identical in the precursors from all three strains. These conserved nucleotides can form a stem and loop structure which is likely to play an important role in the biosynthesis of 5S RNA. Extension secondary and tertiary structure is present in the 5'-precursor-specific segment as concluded from the results of digestion with RNAase T1 both of the isolated segment and the intact precursors. No sequence homology exists between the 3'-precursor-specific segments of the B. licheniformis precursors and those of the other two strains except for a stretch of U residues at the 3-terminus. This stretch of U residues is not immediately preceded by a hairpin loop, however, as expected for a transcription termination signal (20). The question whether the precursors have already undergone processing at the 3'-end, therefore, remains open. The total number of genetically distinct precursor species in B. licheniformis is at least five and at most ten. Most likely each ribosomal RNA cistron produces a separate p5S RNA as is also the case in Bacillus Q.

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