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Contribution of a Thickened Cell Wall and Its Glutamine Nonamidated Component to the Vancomycin Resistance Expressed by Staphylococcus aureus Mu50
- Source :
- Antimicrobial Agents and Chemotherapy. 44:2276-2285
- Publication Year :
- 2000
- Publisher :
- American Society for Microbiology, 2000.
-
Abstract
- Staphylococcus aureus Mu50, which has reduced susceptibility to vancomycin, has a remarkably thickened cell wall with an increased proportion of glutamine nonamidated muropeptides. In addition, Mu50 had enhanced glutamine synthetase and l -glutamine d -fructose-6-phosphate aminotransferase activities, which are involved in the cell-wall peptidoglycan synthesis pathway. Furthermore, significantly increased levels of incorporation of 14 C-labeled d -glucose into the cell wall was observed in Mu50. Unlike a femC mutant S. aureus strain, increased levels of production of nonamidated muropeptides in Mu50 was not caused by lower levels of glutamine synthetase activity but was considered to be due to the glutamine depletion caused by increased glucose utilization by the cell to biosynthesize increased amounts of peptidoglycan. After the cells were allowed to synthesize cell wall in the absence or presence of glucose and glutamine, cells with different cell-wall thicknesses and with cell walls with different levels of cross-linking were prepared, and susceptibility testing of these cells demonstrated a strong correlation between the cell-wall thickness and the degree of vancomycin resistance. Affinity trapping of vancomycin molecules by the cell wall and clogging of the outer layers of peptidoglycan by bound vancomycin molecules were considered to be the mechanism of vancomycin resistance of Mu50. The reduced cross-linking and the increased affinity of binding to vancomycin of the Mu50 cell wall presumably caused by the increased proportion of nonamidated muropeptides may also contribute to the resistance to some extent.
- Subjects :
- Staphylococcus aureus
Glutamine
Cell
Biology
medicine.disease_cause
Microbiology
Cell wall
chemistry.chemical_compound
Bacterial Proteins
Cell Wall
Glutamate-Ammonia Ligase
Mechanisms of Resistance
Glutamine synthetase
medicine
Humans
Pharmacology (medical)
Carbon Radioisotopes
Antibacterial agent
Pharmacology
Vancomycin Resistance
Culture Media
Glucose
Infectious Diseases
medicine.anatomical_structure
chemistry
Vancomycin
Peptidoglycan
medicine.drug
Subjects
Details
- ISSN :
- 10986596 and 00664804
- Volume :
- 44
- Database :
- OpenAIRE
- Journal :
- Antimicrobial Agents and Chemotherapy
- Accession number :
- edsair.doi.dedup.....8c8d8d8f37e0b1d1ce377c42e4e98069
- Full Text :
- https://doi.org/10.1128/aac.44.9.2276-2285.2000