Allelic variation in a peptide-inducible two-component system of Streptococcus pneumoniae.

The peptide SpiP of Streptococcus pneumoniae regulates the induction of a complex signal transduction system spiR1spiR2spiH. Distinct alleles of spiP and the receptor histidine protein kinase gene spiH were recognized in different pneumococcal clones. The spi system in strain KNR7/87 is adjacent to a bacteriocin gene cluster encoding putative double glycine-type bacteriocins, immunity proteins, and translocator proteins. A direct repeat element upstream of the spiR1 promoter and another three potential transcription start sites within the bacteriocin cluster indicate that SpiP functions as an inducing peptide for bacteriocin synthesis in S. pneumoniae.