MOLECULAR CLONING, EXPRESSION, AND CHARACTERIZATION OF DNAK IN STREPTOCOCCUS-PNEUMONIAE

DnaK is known to be highly conserved in all species and is a major imm unogen Streptococcus pneumoniae. To elucidate the role of dnaK in S pn eumoniae, dnaK was cloned in Escherichia coli using a homologous dnaK probe generated by PCR. The His-tagged DnaK was overexpressed in solub le form and purified from E. coli. Alignment of the deduced DnaK amino acid sequence from nucleotide sequences of the cloned dnaK revealed h igh homology with DnaK analogs in E. coli (53%) and Staphylococcus aur eus (73%). However, anti-pneumococcal DnaK antiserum did not crossreac t with DnaK analogs in E. coli, S. aureus and human cells suggesting t hat pneumococcal DnaK might be a good candidate as a vaccine. (C) 1998 Federation of European Microbiological Societies. Published by Elsevi er Science B.V.