Related Experiment Videos
Cell-density-dependent killing of Myxococcus xanthus by autocide AMV
Abstract:
Autocide AMV of Myxococcus xanthus was purified and identified as phosphatidylethanolamine. Alkaline hydrolysis of AMV yielded a high proportion of mono- and diunsaturated fatty acids. The bactericidal activity of AMV on M. xanthus depended upon the density of target cells: the greater the cell density, the greater the killing by AMV. For example, at 2 U of AMV per ml, 0, 50, and 99% killing was measured with 2 X 10(4), 2 X 10(5), and 2 X 10(7) target cells per ml, respectively. The cell-density-dependent activity of AMV was also observed on solid medium. Studies with model lipid compounds suggest that the inhibitory activity of AMV is due to the fatty acid moiety, released from phosphatidylethanolamine by the concerted (enzymatic) activity of many cells. Mutants of M. xanthus selected for resistance to AMI (a mixture of fatty acids) were also resistant to AMV. The possible role of AMV in developmental lysis is discussed.
Insights
Autocide AMV, identified as phosphatidylethanolamine, exhibits cell-density-dependent bactericidal activity against Myxococcus xanthus. Its fatty acid component, released by cell activity, is responsible for this killing effect.
Area of Science:
- Microbiology
- Biochemistry
- Molecular Biology
Background:
- Myxococcus xanthus undergoes developmental lysis, a process potentially involving self-killing mechanisms.
- Autocide AMV (AMV) is a substance produced by M. xanthus with known bactericidal properties.
Purpose of the Study:
- To identify the chemical nature of Autocide AMV.
- To elucidate the mechanism underlying AMV's bactericidal activity.
- To investigate the role of cell density in AMV's efficacy.
Main Methods:
- Purification and chemical identification of AMV.
- Alkaline hydrolysis to analyze fatty acid composition.
- Assays to determine AMV's bactericidal activity at varying M. xanthus cell densities.
- Studies using model lipid compounds.
- Analysis of M. xanthus mutants resistant to fatty acids.
Main Results:
- AMV was identified as phosphatidylethanolamine.
- Alkaline hydrolysis revealed a high proportion of unsaturated fatty acids in AMV.
- AMV's bactericidal activity was directly correlated with M. xanthus cell density.
- Fatty acids released from phosphatidylethanolamine appear to be the active inhibitory component.
- Mutants resistant to fatty acids (AMI) were also resistant to AMV.
Conclusions:
- AMV is a cell-density-dependent bactericidal agent composed of phosphatidylethanolamine.
- The fatty acid moiety of AMV, released through concerted cellular activity, mediates its toxicity.
- AMV may play a role in the developmental lysis of Myxococcus xanthus.