groESL sequence determination, phylogenetic analysis, and species differentiation for viridans group streptococci

The full-length sequences of the groESL genes (also known as cpn10/60) of Streptococcus anginosus, Streptococcus constellatus, Streptococcus gordonii, and Streptococcus sanguis and the near full-length sequence of the groESL genes of Streptococcus intermedius, Streptococcus bovis, Streptococcus mitis, Streptococcus mutans, Streptococcus oralis, and Streptococcus salivarius were determined. The lengths of the groES genes from the 10 species listed above ranged from 282 to 288 bp, and the full-length sequences of groEL determined for 4 species (S. anginosus, S. constellatus, S. gordonii, and S. sanguis) revealed that each was 1,623 bp. The intergenic region (spacer) between the groES and groEL genes varies in size (15 to 111 bp) and sequence between species. The variation of the groES sequences among the species tested was greater (62.1 to 95.1% nucleotide sequence identities) than that of the groEL sequences (77.2 to 95.2% nucleotide sequence identities). Phylogenetic analysis of the groES and groEL genes yielded evolutionary trees similar to the tree constructed by use of the 16S rRNA gene. The intraspecies variation of the spacer was minimal for clinical isolates of some species. The groESL sequence data provide an additional parameter for identification of viridans group streptococcal species.