Acholeplasma laidlawii

Huang, L. and A. Haug. 1974. Regulation of membrane lipid fluidity in Acholeplasma laidlawii Effect of carotenoid pigment content. Biochim. Biophys. Acta 352 361-370. 

Rottem, S. and O. Markowitz. 1979. Carotenoids acts as reinforcers of the Acholeplasma laidlawii lipid bilayer. J. Bacteriol. 140 944—948. 

Tyron, V.V. Pollack, D. Purine metabolism in Acholeplasma laidlawii B novel PPi-dependent nucleoside kinase activity, J, BacterioL, 159, 265-270 (1984)... 

Kahane, L Muhlrad, A. Purification and properties of acetate kinase from Acholeplasma laidlawii. J. Bacteriol., 137, 764-772 (1979)... 

Natural biological membranes were studied from 0 to 50 C 334). The plasma membrane of the microorganism Acholeplasma laidlawii was compared with a model lipid (l,2-diperdeuteropalmitoyl-sn-glycero-3-phosphocholine). The phase transition... 

Along a more biological approach, D. Chapman 116) has described the biosynthetic incorporation of diacetylene acids into the biomembranes of Acholeplasma laidlawii A, an unsaturated fatty acid auxotroph bacterium. As much as 90% of the membrane lipid acyl chains were found to consist of C20-diynoic acid. Upon irradiation with UV-light, the cells and isolated membranes become coloured, due to the crosslinking of lipids by photopolymerization. 

McElhaney, R.N. (1984). The structure and function of the Acholeplasma laidlawii membrane. Biochim. Biophys. Acta 779 1-42. 

Weibull, C., Christiansson, A., and Carlemalm, E. (1983), Extraction of membrane lipids during fixation, dehydration and embedding of Acholeplasma laidlawii-cells for electron microscopy, J. Microsc., 129,201-207. 

Although DSC and other physical techniques have made considerable contributions to the elucidation of the nature of lipid-protein interactions, several outstanding questions remain. For example, it remains to be dehnitively determined whether some integral, transmembrane proteins completely abolish the cooperative gel-to-liquid-crystalline phase transition of lipids with which they are in direct contact or whether only a partial abolition of this transition occurs, as is suggested by the studies of the interactions of the model transmembrane peptides with phospholipids bilayers (see above). The mechanism by which some integral, transmembrane proteins perturb the phase behavior of very large numbers of phospholipids also remains to be determined. Finally, the molecular basis of the complex and unusual behavior of proteins such as the concanavalin A receptor and the Acholeplasma laidlawii B ATPase is still obscure (see Reference 17). 

Figure 5 High-sensitivity DSC heating scans of Acholeplasma laidlawii B eiaidic acid-homogeneous intact ceiis, isoiated membranes and extracted totai membrane iipids dispersed as muitiiameiiar vesicies in water.

McElhaney RN. The influence of membrane lipid composition and physical properties on membrane structure and function in Acholeplasma laidlawii. CRC Crit. Rev. Microbiol. 1989 17 1-32. 

Foht PJ, Quynh MT, Lewis RNAH, McElhaney RN. Quantitation of the phase preferences of the major lipids of the Acholeplasma laidlawii B membrane. Biochemistry 1995 34 13811-13817. Lewis RNAH, McElhaney RN. Acholeplasma laidlawii B membranes contain a lipid (glycxerylphosphoryldiglucosyl diacylgly-cerol) which forms micellar rather than lamellar or reversed phases when dispersed in water. Biochemistry 1995 34 13818-13824. Steim JM, Tonrtellotte ME, Reinert JC, McElhaney RN, Rader RL. Calorimetric evidence for the liquid-crystalline state of lipids in a biomembrane. Proc. Natl. Acad. Sci. U.S.A. 1969 63 104-109. Reinert JC, Steim JM. Calorimetric detection of a membrane lipid phase transition in living cells. Science 1970 168 1580-1582. Melchior DL, Morowitz HJ, Sturtevant JM, Tsong TY. Characterization of the plasma membrane of Mycolplasma laidlawii. Vni. Phase transitions of membrane lipids. Biochim. Biophys. Acta 1970 219 114-122. 

Another specific application is the use of 0.1 pm syringe filters for the removal of mycoplasma in tissue culture work. They are capable of removing 99.99% of three common human mycoplasma species (M. hominis, M. salivarium and M. fermentans) and two common contaminants of fetal calf serum (M. arginini and Acholeplasma Laidlawii) [Hoffman, 1989]. 

Figure 5 Example of an experimental molecular order parameter profile. O, di-palmitoylphosphatidylcholine (DPPC) A, palmitoleicphosphatidylcholine (POPC) , dipalmitoylphosphatidylserine (DPPS) based bilayers X, bilayers derived from Acholeplasma laidlawii. All measurements were taken at the same reduced temperature 0 = (T - Tc)/T = 0.0605 (where = phase transition temperature).

The detailed studies performed by Lindblom, Wieslander, and co-workers on the lipid adjustments of the mycoplasma Acholeplasma laidlawii A are especially interesting (see references 44 and 7 for reviews of these and related experiments). Acholeplasma laidlawii A incorporates exogenous fatty... 

In a continuation of work on membranes, the 1 3C nmr spectra of membranes from Acholeplasma laidlawii grown on 13C-enrichcd palmitic acid were recorded (Metcalfe et al., 1972 1973a Metcalfe, 1972). The enhanced carboxyl resonance was the only peak observed under conditions where no natural abundance 13 C signals were measurable and the temperature exceeded the thermal transition temperature of the lipids in the membranes. The ability to reduce the 13 C nmr spectra of membranes to a few sharp resonances by incorporating 13 C-enriched lipids biosynthetically allows the T, -values to be obtained. 

Figure 9. NMR spectra of the plasma membranes of Acholeplasma laidlawii enriched in palmitic acid labeled at the 13-position (I3-Ai 16 0) and in oleic acid labeled at the 12-position (12-d2 18 1). Spectra were obtained at the growth temperature, 37°C. The temperatures of optimal growth, To, and the calorimetric gel to liquid crystal phase transition of the lipids in the membranes, T, are indicated. Details of sample preparation and spectral acquisition are given in Ref. 23 and 24.

Figure 12. Temperature-dependence of the fraction of liquid crystalline lipid (() and the heterogeneity parameter ("Aj, proportional to the mean square deviation of the order parameter) for the H NMR spectra of Acholeplasma laidlawii membranes shown in Figure 11 (C-14 0-m-d3 90%). The calorimetric phase transition temperature is indicated by Tc. (Unpublished data of H. C. Jarrell, R. Deslauriers, and...

X.L. Cheng, Q.M. Tran, P.J. Foht, R.N. Lewis (2002). The biosynthetic incorporation of short-chain linear saturated fatty acids by Acholeplasma laidlawii B may suppress growth by perturbing membrane lipid polar headgroup distribution. Biochemistry 41 8665-8671. 

Figure 15 Individual Cells of Acholeplasma laidlawii. Its Complex Life Cycle [2339] Reference Appendix 2, Explanations to the Figures...

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