Table 2.

Antagonization of mersacidin by isolated lipid II

Antagonist Antagonist/ antibiotic ratioaMIC (μg/ml) for M. luteus ATCC 4698
Mersa- cidinVanco- mycinActa- gardineBaci- tracin
None0.10.10.80.08
Lipid II5>2.5b >2.5 NDc 0.08
UDP-MurNAc-pentapeptide1000.1>10NDND
UDP-MurNAc-pentapeptide and GlcNAc1000.1NDNDND
Moenomycind 170.05NDNDND
Oligomeric M. luteuspeptidoglycane 0.2>16NDND
GlcNAc-MurNAc-Ala–d-iso-Gln1000.1NDNDND
1,0000.15
GlcNAc-MurNAc-Ala–d-iso-Gln and PPi f 1000.1NDNDND
1,0000.15
GlcNAc and UDP-GlcNAc1000.1NDNDND
Bisacetyl-Lys–d-Ala–d-Ala100.10.20.8ND
1000.1>200.8
  • a Antagonists were diluted along with the antibiotics, and throughout the dilution series the indicated molar ratio was kept constant.

  • b >, complete antagonization at the highest concentration tested.

  • c ND, not determined.

  • d A subinhibitory concentration of 1.5 μg/ml, corresponding to 40% of the MIC, was used.

  • e 2.3 mg of lysozyme-digested cell walls was mixed with 4 μg of the antibiotic and diluted concomitantly.

  • f The pyrophosphate (PPi) concentration was kept constant at 0.5 mM throughout the dilution series.