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Cytoplasmic peptidoglycan intermediate levels in Staphylococcus aureus.
Harika Vemula1, Navid J Ayon1, William G Gutheil1
1Division of Pharmaceutical Sciences, School of Pharmacy, University of Missouri-Kansas City, 2464 Charlotte Street, Kansas City, MO 64108, USA.
Biochimie
|November 28, 2015
Summary
This study quantifies Staphylococcus aureus peptidoglycan intermediates, revealing high UDP-MurNAc levels and enzyme saturation critical for bacterial growth. These findings offer insights into bacterial cell wall synthesis.
Area of Science:
- Microbiology
- Biochemistry
- Molecular Biology
Background:
- Bacterial cell wall synthesis is crucial for survival.
- Peptidoglycan (PG) biosynthesis involves complex cytoplasmic intermediates.
- Understanding these pathways is key to developing new antibiotics.
Purpose of the Study:
- To quantitatively determine intracellular peptidoglycan intermediate levels in Staphylococcus aureus.
- To compare these levels with enzyme kinetics and known pathways.
- To identify potential differences with other bacteria like Escherichia coli.
Main Methods:
- Utilized ion pairing LC-MS/MS in negative mode for UDP-linked intermediates.
- Employed Marfey's reagent derivatization in positive mode for amine intermediates.
- Quantified total PG to estimate the rate of PG synthesis.
Main Results:
- UDP-linked intermediates ranged from 1.4 μM to 1200 μM (UDP-MurNAc).
- Amine intermediates varied from 860 μM to 260 mM.
- Estimated PG synthesis rate at 690 μM/min, with total UDP-pool sustaining growth for 3.6 min.
- Identified enzymes MurA, Z, and C as >80% saturated, while MurB was <5% saturated.
- Observed significantly higher UDP-MurNAc levels in S. aureus compared to E. coli.
Conclusions:
- S. aureus possesses a substantial pool of PG intermediates, particularly UDP-MurNAc.
- Enzyme saturation levels suggest potential bottlenecks or regulatory points in the PG synthesis pathway.
- Metabolite profiles differ between S. aureus and E. coli, impacting our understanding of PG synthesis across species.
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