Diversity of domain V of 23S rRNA gene sequence in different Enterococcus species

The highly conserved central loop of domain V of 23S RNA (nucleotides 2042 to 2628; Escherichia coli numbering) is implicated in peptidyltransferase a ctivity and represents one of the target sites for macrolide, lincosamide, and streptogramin B antibiotics. DNA encoding domain V (590 bp) of several species of Enterococcus was amplified by PCR Twenty enterococcal isolates w ere tested, including Enterococcus faecium (six isolates), Enterococcus fae calis, Enterococcus avium, Enterococcus durans, Enterococcus gallinarum, En terococcus casseliflavus (two isolates of each), and Enterococcus raffinosu s, Enterococcus mundtii, Enterococcus malodoratus, and Enterococcus hirae t one isolate of each). For all isolates, species identification by biochemic al testing was corroborated by 16S rRNA gene sequencing, The sequence of do main V of the 23S rRNA gene from E, faecium and E, faecalis differed from t hose of all other enterococci, The domain V sequences of E, durans and E, h irae were identical. This was also true for E, gallinarum and E, casselifla vus, E, avium differed from E, casseliflavus by 23 bases, from E, durans by 16 bases, and from E, malodoratus by 2 bases. E, avium differed from E, ra ffinosus by one base. Despite the fact that domain V is considered to be hi ghly conserved, substantial differences were identified between several ent erococcal species.