Subcloning the Stress-induced El Gene from the Bacterial Predator, Bdellovibrio Bacteriovorus .

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The EL and EL chaperonin proteins are essential for bacterial cell survival, assisting various cytoplasmic proteins to refold correctly after exposure to a stressful environment. It is hypothesized that Bdellovibrio experiences a stressful environment during invasion of the host periplasm; this is similar to the stress experienced by symbiotic and pathogenic bacteria as the invade the cytoplasm of eukaryotic cells. Previous work resulted in the isolation of a EL-like gene from Bdellovibrio on a cosmid vector. Attempts were made to subclone this gene onto a more manageable vector for intensive analysis. A new EL mutant E. coli strain was used to identify possible subclones; wild type EL genes in this mutant lead to temperature resistance, UV resistance, and the ability to grow on rhamnose. Unfortunately, the strain was extremely difficult to transform with plasmid DNA, making subclone evaluation problematic. Finally, reporter gene technology was evaluated in Bdellovibrio. A broad host range plasmid containing the E. coli grpE (related to EL) promoter controlling luciferase genes was shown to induce light production under stressful conditions. As a first test, this plasmid (pGrpE-lux) was moved into Bdellovibrio by conjugation. No light was produced, under stressed or normal conditions. The E. coli grpE promoter was clearly not functional in Bdellovibrio, but the Bdellovibrio groEL promoter in this plasmid would be useful in monitoring stress throughout the lifecycle of this bacterial predator.


M. O. Martin




Support provided by:Howard Hughes Medical Institute

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