Studies of heterologous expression of a mycobacterial glutathione s-transferase gene
Date
2010-04-16T08:41:23Z
Authors
Adetunji, Olugbade Adebayo
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Abstract
Resistance to antibiotics still poses a major challenge to human and animal health as a
result of wide spread dissemination of resistance genes. Study of the evolutionary
origin of these determinants is of importance in order to understand how the
mechanisms involved arose in the first place. Two approaches were used to study
antibiotic resistance from the evolutionary point of view; a model system of
heterologous expression of Gram positive DNAs in a Gram negative background
giving rise to macrolide resistance, and expression of the Gram positive glutathione-
S-transferase (gst) gene from Mycobacterium in both Gram positive and Gram
negative backgrounds.
Expression of the gst gene in Escherichia coli conferred a 3× increase in MIC in
kanamycin and streptomycin and a ~ 2 fold increase for chloramphenicol. In the Gram
positive Rhodococcus erythropolis ATCC 4277 it gave a ~ 5× increase in MIC for
spectinomycin, streptomycin and nalidixic acid, while kasugamycin and
chloramphenicol showed a 4× increase. Inactivation assay experiments also revealed
the possibility of a novel chloramphenicol inactivation. Attempts made to create
mutants with increased resistance by spontaneous selection, chemical mutagenesis or
by use of an E. coli mutator strain were unsuccessful.