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Binding of lectins to membranes of mycoplasmas from aging cultures
Abstract:
The binding of iodinated concanavalin A (Con A) and Ricinus communis agglutinin (RCA) to intact cells and isolated membranes of Acholeplasma laidlawii, Mycoplasma hominis and Mycoplasma capricolum decreased with the progression of the culture from the mid- to the late-logarithmic phase of growth. The binding of the lectins to Acholeplasma laidlawii membranes had no significant effect on membrane fluidity, as assessed by electron-paramagnetic resonance spectroscopy of spin-labelled fatty acids, and had no effect on several membrane-associated enzymic activities. Temperature affected the binding of Con A and RCA in an opposite manner: the binding of Con A increased, whereas that of RCA decreased, on raising the temperature from 4 degrees C to 37 degrees C. No significant difference in lectin binding was found between oleate- and elaidate-enriched membranes at low temperatures where the former was in the liquid-crystalline state and the latter in the gel state, suggesting that membranes fluidity does not influence the binding of Con A and RCA to Acholeplasma laidlawii membranes.
Insights
Lectins like concanavalin A (Con A) and Ricinus communis agglutinin (RCA) binding to mycoplasma cells decreases with culture growth. Membrane fluidity and enzyme activity were unaffected, but temperature altered lectin binding differently.
Area of Science:
- Microbiology
- Biochemistry
- Cell Biology
Background:
- Mycoplasma species are wall-less bacteria with unique cell membrane compositions.
- Lectins are proteins that bind carbohydrates, often used to study cell surface structures.
- Concanavalin A (Con A) and Ricinus communis agglutinin (RCA) are well-characterized plant lectins.
Purpose of the Study:
- To investigate the binding characteristics of Con A and RCA to mycoplasma cell membranes.
- To determine the influence of growth phase and membrane composition on lectin binding.
- To assess the effect of lectin binding on membrane fluidity and enzyme activity.
Main Methods:
- Utilized iodinated Con A and RCA for binding assays.
- Employed electron-paramagnetic resonance spectroscopy to measure membrane fluidity.
- Assessed membrane-associated enzyme activities.
- Investigated lectin binding across different growth phases and membrane lipid compositions (oleate vs. elaidate).
Main Results:
- Lectin binding to intact cells and isolated membranes decreased as cultures progressed from mid- to late-logarithmic phase.
- Binding of Con A and RCA to Acholeplasma laidlawii membranes did not significantly alter membrane fluidity or enzyme activities.
- Temperature influenced lectin binding antagonistically: Con A binding increased with temperature, while RCA binding decreased.
- No significant difference in lectin binding was observed between oleate- and elaidate-enriched membranes, irrespective of membrane state (liquid-crystalline vs. gel).
Conclusions:
- Lectin binding to mycoplasma cells is modulated by growth phase.
- Membrane fluidity and associated enzyme activities are not significantly impacted by Con A or RCA binding in Acholeplasma laidlawii.
- Temperature plays a differential role in the binding of Con A and RCA.
- Membrane fluidity is not a primary determinant for Con A and RCA binding to Acholeplasma laidlawii membranes.