Frequency-selective REDOR and spin-diffusion relays in uniformly labeled whole cells

Area of Science:

• Biochemistry
• Microbiology
• Spectroscopy

Background:

• Bacterial cell walls contain peptidoglycan and teichoic acids, crucial for function.
• Teichoic acid d-alanine's amine is typically lost during isolation, requiring whole-cell analysis.
• Solid-state NMR is a non-perturbative method for analyzing bacterial cell walls.

Purpose of the Study:

• To develop and apply a new NMR sequence for detecting specific molecular contributions in whole bacterial cells.
• To identify the unique amine contribution in uniformly labeled Staphylococcus aureus.
• To attribute this amine to d-alanine within teichoic acid.

Main Methods:

• Utilized a novel NMR sequence combining frequency-selective REDOR (fsREDOR) and spin diffusion.
• Employed uniformly (13)C- and (15)N-labeled Staphylococcus aureus whole cells.
• Applied fsREDOR for selective (13)C observation and (15)N dephasing to overcome labeling complexities.

Main Results:

• Successfully detected a unique amine signal in Staphylococcus aureus whole cells.
• The detected amine nitrogen is spatially close to teichoic acid ribitol carbons and alanine methyl carbons.
• The amine's carbonyl environment was consistent with its ester linkage in teichoic acid.

Conclusions:

• The novel NMR sequence enables the detection of teichoic acid d-alanine in intact bacterial cells.
• This method provides insights into the structural organization and chemical environment of cell wall components.
• Advances the understanding of bacterial cell wall architecture and the role of teichoic acids.