Peptidoglycan and Teichoic Acid Levels and Alterations in S. aureus by Cell-Wall and Whole-Cell NMR

• Published in: Biochemistry (Easton) Vol. 57; no. 26; pp. 3966 - 3975
• Main Authors: Romaniuk, Joseph A. H., Cegelski, Lynette
• Format: Journal Article
• Language: English
• Published: 11-06-2018
• ISSN: 0006-2960; 1520-4995
• DOI: 10.1021/acs.biochem.8b00495

Gram-positive bacteria surround themselves with a multi-layered macromolecular cell wall that is essential to cell survival and serves as a major target for antibiotics. The cell wall of
S. aureus
is composed of two major structural components, peptidoglycan (PG) and wall teichoic acid (WTA), together creating a heterogeneous and insoluble matrix that poses a challenge to quantitative compositional analysis. Here, we present
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C CPMAS solid-state NMR spectra of intact cell walls, purified PG, and purified WTA. The spectra reveal the clear molecular differences in the two polymers and enable quantification of PG and WTA in isolated cell walls, an attractive alternative to estimating teichoic acid content from a phosphate analysis of completely pyrolyzed cell walls. Furthermore, we discovered that unique PG and WTA spectral signatures could be identified in whole-cell NMR spectra and used to compare PG and WTA levels among intact bacterial cell samples. The distinguishing whole cell
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C NMR contributions associated with PG include the GlcNAc-MurNAc sugar carbons and glycyl alpha-carbons. WTA contributes carbons from the phosphoribitol backbone. Distinguishing
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N spectral signatures include glycyl amide nitrogens in PG and the esterified D-alanyl amine nitrogens in WTA.
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C NMR analysis was performed with samples at natural abundance and included ten whole-cell sample comparisons. Changes consistent with altered PG and WTA content were detected in whole-cell spectra of bacteria harvested at different growth times and in cells treated with tunicamycin. This use of whole-cell NMR provides quantitative parameters of composition in the context of whole cell activity.