GENETIC IDENTIFICATION OF EXPORTED PROTEINS IN STREPTOCOCCUS-PNEUMONIAE

A strategy was developed to mutate and genetically identify exported p roteins in Streptococcus pneumoniae. Vectors were created and used to screen pneumococcal DNA in Escherichia coli and S. pneumoniae for tran slational gene fusions to alkaline phosphatase (PhoA). Twenty five Pho A+ pneumococcal mutants were isolated and the loci from eight of these mutants showed similarity to known exported or membrane-associated pr oteins. Homologues were found to: (i) protein-dependent peptide permea ses, (ii) penicillin-binding proteins, (iii) Clp proteases, (iv) two-c omponent sensor regulators, (v) the phosphoenolpyruvate: carbohydrate phosphotransferase permeases, (vi) membrane-associated dehydrogenases, (vii) P-type (E1E2-type) cation transport ATPases, (viii) ABC transpo rters responsible for the translocation of the RTX class of bacterial toxins. Unexpectedly one PhoA+ mutant contained a fusion to a member o f the DEAD protein family of ATP-dependent RNA helicases suggesting ex port of these proteins.