Related Experiment Videos
Incorporation and modification of exogenous phosphatidylcholines by mycoplasmas
Abstract:
The uptake and modification of exogenous phosphatidylcholine (PC) by several Mycoplasma and Spiroplasma species was investigated. While in most Mycoplasma species and in all Spiroplasma species tested the PC appears to be incorporated unchanged from the growth medium, the PC of M. gallisepticum, M. pulmonis, and M. pneumoniae was disaturated PC, apparently formed by modification of 1-saturated-2-unsaturated PC from the growth medium. The modification of the exogenous PC by M. gallisepticum was inhibited by chloramphenicol under conditions that did not affect de novo synthesis of phosphatidylglycerol. A low activity of an endogenous phospholipase A was detected in native M. gallisepticum membranes. The activity was markedly stimulated by treating the membranes with low concentrations of the nonionic detergents. The PC modification was affected by the fatty acid composition of the exogenous PC species. Diunsaturated, 1-saturated-2-unsaturated, and 1-unsaturated-2-saturated PCs were modified to various extents, whereas the disaturated dipalmitoyl PC (DPPC) was not. Both modified and unmodified PCs were incorporated by the cells, but the unmodified DPPC was incorporated at a lower rate and to a lesser extent. The possibility that the incorporation of DPPC into M. gallisepticum cells is associated with the formation of intracytoplasmic membranes is discussed.
Insights
Certain Mycoplasma species modify exogenous phosphatidylcholine (PC) into disaturated forms, unlike other species that incorporate it unchanged. This modification involves phospholipase A and is influenced by PC fatty acid composition.
Area of Science:
- Microbiology
- Cell Biology
- Biochemistry
Background:
- Exogenous lipids are crucial for the growth of many Mycoplasma and Spiroplasma species.
- Phosphatidylcholine (PC) is a common phospholipid in biological membranes.
Purpose of the Study:
- To investigate the uptake and modification of exogenous phosphatidylcholine (PC) by Mycoplasma and Spiroplasma species.
- To identify the mechanisms and factors influencing PC modification in specific Mycoplasma species.
Main Methods:
- Culturing of Mycoplasma and Spiroplasma species with exogenous PC.
- Analysis of PC composition in cell membranes using techniques like chromatography.
- Enzyme assays to detect phospholipase A activity in M. gallisepticum membranes.
- Inhibition studies using chloramphenicol.
Main Results:
- Most Mycoplasma and all Spiroplasma species incorporated exogenous PC unchanged.
- M. gallisepticum, M. pulmonis, and M. pneumoniae modified exogenous PC into disaturated forms.
- An endogenous phospholipase A in M. gallisepticum membranes, stimulated by detergents, was implicated in PC modification.
- PC modification was dependent on the fatty acid composition of the exogenous PC, with DPPC being resistant to modification.
- Unmodified DPPC was incorporated at a lower rate by M. gallisepticum.
Conclusions:
- Specific Mycoplasma species possess the capability to modify exogenous phosphatidylcholine.
- Phospholipase A activity plays a role in the conversion of unsaturated PC to disaturated PC in M. gallisepticum.
- The fatty acid composition of PC influences its incorporation and modification by Mycoplasma species.