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Chapter 13 : Characterization of the Legionella pneumophila DnaJ-Like Protein DjlA: Virulence Attenuation of djlA Mutants
Characterization of the Legionella pneumophila DnaJ-Like Protein DjlA: Virulence Attenuation of djlA Mutants, Page 1 of 2< Previous page Next page > /docserver/preview/fulltext/10.1128/9781555817985/9781555812300_Chap13-1.gif /docserver/preview/fulltext/10.1128/9781555817985/9781555812300_Chap13-2.gif
The bacterial DnaJ-like protein DjlA is composed of two functional domains, an N-terminal transmembrane domain of type III topology and a J domain at the C terminus. The authors investigated the Legionella pneumophila DjlA protein. The plasmid constructs were used to transform L. pneumophila and Escherichia coli strains. Overexpression of the L. pneumophila djlA gene in E. coli K-12 resulted in a mucoid phenotype due to colanic acid capsule production. The djlA mutants of all four strains did not exhibit alterations in growth rate in buffered yeast extract (BYE) broth when compared with the appropriate wild type, suggesting that djlA is not an essential gene in L. pneumophila. Incubation with a pool of 40% normal human serum revealed that the djlA mutants were as serum-resistant as the parent wild-type strains. The obtained CFU counts for strains R458 and Corby and the corresponding mutants are depicted. Thus, deletion of the djlA gene resulted in reduced virulence in all investigated L. pneumophila strains. To our knowledge, this is the first report of an influence on virulence by the djlA gene product in pathogenic bacteria. However, the authors do not know by which mechanism virulence attenuation is achieved in the L. pneumophila djlA mutants.