Intervening sequences in 23S rRNA genes and 23S rRNA fragmentation in Taylorella asinigenitalis UCD-1T strain

PCR was performed with Taylorella asinigenitalis UCD-1(T) using two primer pairs constructed in silico for the amplification of the intervening sequences (IVSs) in the first quarter and central regions of the 23S rRNA gene. Following TA cloning and sequencing, the strain was identified to carry heterogeneous and multiple IVSs. Two similar tandem repeat units of 25 and 24 base pairs (bp) with unknown function(s) were identified within the two IVSs in the central region. Secondary structure models of IVSs, containing stem and loop structures, were demonstrated. Although 16S rRNA and 4-5S RNA species were identified in the purified RNA fraction, no 23S rRNAs were evident, resulting in the occurrence of some smaller RNA fragments from approximately 500 to 1600 bp, in length. Thus, the 23S rRNA primary transcripts may be cleaved into some smaller fragments and IVSs. No IVS transcript was detected by northern blot hybridization analysis. The present and previous results strongly demonstrate the occurrence of heterogeneous and multiple IVSs in 23S rRNA gene sequences and 23S rRNA fragmentation, in T. asinigenitalis.