Competence for genetic transformation in encapsulated strains of Streptococcus pneumoniae: two allelic variants of the peptide pheromone

Competence genes were found in all 42 encapsulated strains of different serotypes in a nucleotide sequence analysis of comC, the gene encoding the 17-residue competence-stimulating peptide (CSP) of Streptococcus pneumoniae. Thirteen strains revealed the presence of a new allele, comC2, including the type 3 Avery strain A66. All other strains carried a gene, comC1, identical to that originally described for strain Rx1. Competence was induced in the 42 strains using CSP-1 and CSP-2 synthetic peptides, with 48% of the strains becoming competent after adding the synthetic peptide. None were transformable without the added peptides.