IDENTIFICATION, CLONING, AND SEQUENCING OF DNA ESSENTIAL FOR ENCAPSULATION OF STREPTOCOCCUS-PNEUMONIAE

This paper reports the cloning and sequencing of a region of DNA from Streptococcus pneumoniae serotype 3 surrounding transposon Tn916, inse rtion of which was previously shown to result in lack of expression of the extracellular capsule. Sequence analysis revealed that the transp oson inserted into a consensus insertion site 71 bp from the 5' end of the cloned fragment. Within the clone, 3' downstream regions from two different pneumococcal lytA genes were identified, as well as a putat ive 194 AA open reading frame (ORF1). Moreover, two copies of the repe at element BOX, oriented in opposite directions, were located immediat ely 3' of orf1. Within the region bounded by the first pair of interna l sequencing primers, analysis revealed that the fragment amplified by PCR was always of the same size. Moreover, Southern blotting showed t hat for all serotypes examined to date, homology exists with the clone d fragment. These results indicate that this region of the chromosome is highly conserved and, taken together with other independently deriv ed data, suggest that interruptions or deletions within this DNA lead to unencapsulation.