The effect of NAG-thiazoline on morphology and surface hydrophobicity of Escherichia coli

The beta-hexosaminidase inhibitor and structural analog of the putative oxazolium reaction intermediate of lytic transglycosylases, N-acetylglucosamine thiazoline (NAG-thiazoline), was synthesized in 46% overall yield and tested as an inhibitor of Escherichia coli growth. NAG-thiazoline, at concentrations up to 1 mg/ml, was not found to affect the viability of E. coli DH5alpha. However, the compound did induce morphological changes to the cells. Growth of cells in the presence of NAG-thiazoline caused an apparent inhibition of the biosynthesis of the cylindrical regions of the cells such that they became much shorter in length. The surface of these shorter cells was found to be much less hydrophobic compared to untreated cells as determined by the bacterial adhesion to hydrocarbon (BATH) assay. In addition, the co-administration of NAG-thiazoline with 1.7 x MIC concentrations of ampicillin prevented cell lysis suggesting that the compound inhibited autolytic enzymes, in particular the lytic transglycosylases.