The dynamic structure of the Escherichia coli cell envelope as probed by 15N nuclear magnetic resonance spectroscopy

Abstract

Proton decoupled 15N NMR spectroscopy is shown to be a useful tool for probin the dynamic structure of the bacterial cell envelope. The proton decoupled 15N NMR spectra of Escherichia coli whole cells, cell envelopes and outer membranes were obtained and displayed resonances originating from protein side-chain groups, phosphatidylethanolamine, and peptidoglycan. Removal of phospholipids from the cell envelope resulted in a decrease in the motional freedom of peptidoglycan and cell envelope proteins. The mobility of the protein Arg side-chain groups is increased in the absence of peptidoglycan. These data provide insights into the effect of supramolecular organization on the dynamic structure of the E. coli cell envelope.