Functional characterization of glucosamine-6-phosphate synthase (GlmS) in Salmonella enterica serovar Enteritidis

Salmonella is a threat to public health due to consumption of contaminated food. Screening of a transposon library identified a unique mutant that was growth and host cell binding deficient. The objective of this study was to determine the functional role of glucosamine-6-phosphate synthase (GlmS) in the biology and pathogenesis of Salmonella. To examine this, we created a glmS mutant (Delta glmS) of Salmonella and examined the effect on cell envelope integrity, growth, metabolism, and pathogenesis. Our data indicated Delta glmS was defective in growth unless media were supplemented with d-glucosamine (d-GlcN). Examination of the bacterial cell envelope revealed that Delta glmS was highly sensitive to detergents, hydrophobic antibiotics, and bile salts compared to the wild type (WT). A release assay indicated that Delta glmS secreted higher amounts of beta-lactamase than the WT in culture supernatant fractions. Furthermore, Delta glmS was attenuated in cell culture models of Salmonella infection. Taken together, this study determined an important role for GlmS in the pathogenesis and biology of Salmonella.