Cross-Link Formation and Peptidoglycan Lattice Assemblyin the FemA Mutant of Staphylococcus aureus

摘要

Staphylococcus aureus FemA mutant grown in the presence of an alanine-racemase inhibitor was labeled with d-[1-¹³C]alanine, l-[3-¹³C]alanine, [2-¹³C]glycine, and l-[5-¹⁹F]lysine to characterize some details of the peptidoglycan tertiary structure. Rotational-echo double-resonance (REDOR) NMR of isolated cell walls was used to measure internuclear distances between ¹³C-labeled alanines and ¹⁹F-labeled lysine incorporated in the peptidoglycan. The alanyl ¹³C labels were preselected for REDOR measurement by their proximity to the glycine label using ¹³C–¹³C spin diffusion. The observed ¹³C–¹³C and ¹³C–¹⁹F distances are consistent with a tightly packed, hybrid architecture containing both parallel and perpendicular stems in a repeating structural motif within the peptidoglycan.