MOLECULAR CHARACTERIZATION OF PCPA - A NOVEL CHOLINE-BINDING PROTEIN OF STREPTOCOCCUS-PNEUMONIAE

The gene pcpA that encodes a novel pneumococcal choline-binding protei n has been cloned and characterized. Northern blot analysis revealed t hat pcpA is expressed during the exponential phase of growth of pneumo cocci as a monocistronic transcript of about 2.3 kb. The transcription start site has been located 132 bp upstream of the start codon and th e proposed -35 and -10 boxes that are highly similar to those of the t ypical sigma(70) promoters from Escherichia coli. This gene encodes a putative 79 kDa protein that contains a typical C-terminal choline-bin ding domain (ChBD). The ChBD of PcpA is built up by 11 identical motif s of 20 amino acids plus a tail of 19 amino acids, which represents th e longest ChBD that has been characterized so far. Interestingly, two tandem arrays of five characteristic amphipatic leucine reach repeats (LRRs) of 22-26 amino acids in length have been found in the N-termina l region of PcpA. Since LRRs have been proposed to be involved in prot ein-protein and protein-lipid interactions our finding suggests a role for PcpA in pneumococcal adhesion. (C) 1998 Federation of European Mi crobiological Societies. Published by Elsevier Science B.V. Ali rights reserved.