@article{mbs:/content/journal/micro/10.1099/00221287-143-3-823, author = "Naïmi, Afaf and Beck, Geneviéve and Branlant, Christiane", title = "Primary and secondary structures of rRNA spacer regions in enterococci", journal= "Microbiology", year = "1997", volume = "143", number = "3", pages = "823-834", doi = "https://doi.org/10.1099/00221287-143-3-823", url = "https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-143-3-823", publisher = "Microbiology Society", issn = "1465-2080", type = "Journal Article", keywords = "23S-5S rRNA spacer", keywords = "tRNAAla", keywords = "enterococci", keywords = "16S-23S rRNA spacer", abstract = "The 16S-23S and 23S-5S rRNA spacer DNA regions (spacer regions 1 and 2, respectively) from Enterococcus faecalis, Enterococcus faecium, Enterococcus hirae, Enterococcus durans and Enterococcus mundtii were amplified by PCR. Their nucleotide sequences were established and a secondary structure model showing the interaction between the two spacer regions was built. Whereas lactococci and Streptococcus sensu stricto are characterized by a single type of spacer region 1, the enterococci show a high degree of variability in this region; thus the spacer regions 1 with and without tRNAAlawere characterized. However, as shown for lactococci and Streptococcus sensu stricto, the tRNAAlagene does not encode the 3'-terminal CCA trinucleotide. A putative antitermination signal is found downstream from the tRNAAlagene. Based on comparison with Lactococcus lactis and Streptococcus thermophilus, a double-stranded processing stem is proposed. In E. hirae, one of the three different types of spacer region 1 contains no tRNAAla, but displays a 107 nt insertion that forms a long stem-loop structure. A similar insertion (115 nt in length) was found in E. faecium and base compensatory mutations preserve the ability to form the long stem-loop structure. Such insertions may correspond to mobile intervening sequences, as found in the 23S rRNA coding sequences of some Gram-negative bacteria. The spacer regions 1 and 2 from the three subgroups of streptococci were compared, and except for the tRNAAlagene and the double-stranded processing sites, little similarity was found, which opens large possibilities for future development of DNA-based typing methods.", }