DIFFERENTIATION OF CHLAMYDIA SPP BY SEQUENCE DETERMINATION AND RESTRICTION-ENDONUCLEASE CLEAVAGE OF RNASE-P RNA GENES

The amplification of DNA from Chlamydia trachomatis by PCR with degene rated primers yielded a 345-bp fragment of the putative RNase P RNA ge ne. From the deduced DNA sequence of this gene in C. trachomatis, a mo dified primer pair was designed, The primer pair was subsequently used to obtain the corresponding gene products from Chlamydia pneumoniae a nd Chlamydia psittaci. Sequence comparisons revealed similarities of 7 6.6% between C. trachomatis and C. pneumoniae, 79.5% between C. tracho matis and C. psittaci, and 84.7% between C. pneumoniae and C. psittaci . Furthermore, the three species were differentiated by fragment lengt h polymorphism analysis after restriction enzyme cleavage of the PCR p roducts. Sequence variations among 14 serotypes of C. trachomatis were confined to one purine base substitution in the putative RNase P RNA gene of lymphogranuloma venereum strains L1 to L3. Complete sequence s imilarity was found for nine strains of C. pneumoniae of different geo graphic origins. Taken together, our results indicate a possibility of the general application of this method in clinical bacteriology, Anal ysis of the secondary structures of the putative RNase P RNA genes fro m the different Chlamydia species suggested that a novel structural el ement in the domain of RNase P RNA is involved in base pairing with th e 3'-terminal CCA motif of a tRNA precursor. This structure has not pr eviously been found among RNase P RNAs of members of the division Bact eria.