Method Revealing Bacterial Cell-wall Architecture by Time-dependent Isotope Labeling and Quantitative Liquid Chromatography/mass Spectrometry
Authors
Affiliations
The molecular details of the biosynthesis and resulting architecture of the bacterial cell wall remain unclear but are essential to understanding the activity of glycopeptide antibiotics, the recognition of pathogens by hosts, and the processes of bacterial growth and division. Here we report a new strategy to elucidate bacterial cell-wall architecture based on time-dependent isotope labeling of bacterial cells quantified by liquid chromatography/accurate mass measurement mass spectrometry. The results allow us to track the fate of cell-wall precursors (which contain the vancomycin-binding site) in Enterococcus faecium, a leading antibiotic-resistant pathogen. By comparing isotopic enrichments of postinsertionally modified cell-wall precursors, we find that tripeptides and species without aspartic acid/asparagine (Asp/Asn, Asx) bridges are specific to mature cell wall. Additionally, we find that the sequence of cell-wall maturation varies throughout a cell cycle. We suggest that actively dividing E. faecium cells have three zones of unique peptidoglycan processing. Our results reveal new organizational characteristics of the bacterial cell wall that are important to understanding tertiary structure and designing novel drugs for antibiotic-resistant pathogens.
Espinosa J, Lin T, Estrella Y, Kim B, Molina H, Hang H Biochemistry. 2020; 59(46):4470-4480.
PMID: 33136372 PMC: 8191637. DOI: 10.1021/acs.biochem.0c00755.
Absolute Quantitation of Oxidizable Peptides by Coulometric Mass Spectrometry.
Zhao P, Zare R, Chen H J Am Soc Mass Spectrom. 2019; 30(11):2398-2407.
PMID: 31429055 DOI: 10.1007/s13361-019-02299-z.
Bacterial cell wall composition and the influence of antibiotics by cell-wall and whole-cell NMR.
Romaniuk J, Cegelski L Philos Trans R Soc Lond B Biol Sci. 2015; 370(1679).
PMID: 26370936 PMC: 4632600. DOI: 10.1098/rstb.2015.0024.
Nygaard R, Romaniuk J, Rice D, Cegelski L Biophys J. 2015; 108(6):1380-1389.
PMID: 25809251 PMC: 4375516. DOI: 10.1016/j.bpj.2015.01.037.
Cross-link formation and peptidoglycan lattice assembly in the FemA mutant of Staphylococcus aureus.
Kim S, Singh M, Sharif S, Schaefer J Biochemistry. 2014; 53(9):1420-7.
PMID: 24517508 PMC: 3985804. DOI: 10.1021/bi4016742.