Cloning, sequencing, and chromosomal location of a putative class-II aldolase gene from Streptococcus pneumoniae.

The nucleotide sequence of a 1620-bp chromosomal fragment from Streptococcus pneumoniae, containing a putative class-II aldolase gene, has been determined. The N-terminal amino acid (aa) sequence of S. pneumoniae class-II aldolase protein allowed us to determine the initiation site for the putative aldolase gene, and a molecular weight of 31,274 Da was predicted for the protein, after removal of the N-terminal methionine. Northern hybridization and primer extension analysis showed a 1100-nucleotide transcript with a transcription start site located 43 or 42 bp upstream of the start codon. Southern hybridization studies indicated that the putative class-II aldolase gene was in the ApaI fragment 6, SmaI fragment 9, and SacII fragment 12 or 13 of the physical map of S. pneumoniae chromosome. Southern hybridization analysis and partial sequencing performed in another eight streptococcus species, belonging to six different phylogenetic groups, suggested that a class-II aldolase gene with a considerable DNA homology to that of the S. pneumoniae, could exist in these streptococcal species.