The Effect of Aberrant Protein Synthesis on the Production of Capsular Polysaccharide in Escherichia coli B23

Streptomycin, an aminoglycoside, binds to and modifies prokaryotic ribosomes leading to a decrease in protein synthesis and the production of mistranslated proteins. Previous studies reported that Escherichia coli B23, under sub-lethal concentrations of streptomycin, exhibited an increase in capsule polysaccharide (CPS). The mechanism through which this increase in CPS occurs was unknown. In this investigation, we hypothesized that the increase in CPS in Escherichia coli B23 correlated with the increase in mistranslated protein and not simply due to a decrease in protein synthesis. Mistranslation in protein was measured by changes in the Michaelis constant (KM) and maximum reaction rate (Vmax) of induced βgalactosidase while CPS production and protein synthesis was measured using an anthrone assay and optical density respectively. Our results are inconclusive on the correlation between protein mistranslation and CPS production but indicate that decreased protein synthesis does not consistently correlate with an increase in CPS.