Cloning and characterization of the Brucella ovis heat shock protein DnaK functionally expressed in Escherichia coli. |
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Authors: | M F Cellier J Teyssier M Nicolas J P Liautard J Marti and J Sri Widada |
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Institution: | Département Biologie-Santé, Institut National de la Santé et de la Recherche Médicale U-65, Université Montpellier II, France. |
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Abstract: | The Brucella ovis dnaK gene, homolog to the eukaryotic hsp70 genes, was cloned by using a Drosophila melanogaster probe. Comparison of B. ovis and Escherichia coli sequences revealed a similar organization for the dnaK and dnaJ genes and putative regulatory signals. In E. coli transfected with the cloned fragment, B. ovis hsp70 was expressed at 30 and 50 degrees C apparently under the control of its own promoter. The recombinant protein and a B. ovis native protein displaying the same molecular weight were both recognized by anti-E. coli DnaK serum. Native B. ovis protein was also recognized by sera of sheep either infected or vaccinated with an attenuated Brucella strain, suggesting that Brucella hsp70 could be up-regulated during host colonization. A thermosensitive E. coli dnaK mutant transfected with the cloned fragment recovered colony-forming ability at 42 degrees C, showing that the B. ovis DnaK protein could behave as a functional heat shock protein in E. coli. |
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