Polyprenyl phosphates

Pozzi, G., Birault, V., Werner, B. (1996). Single-chain polyprenyl phosphates form primitive membranes. Angew. Chem. Int. Ed. Engl, 35, 177-9. 

Substances that interfere with the formation of polyprenyl phosphates are of 3 types (1) those that interfere with the biosynthesis of polyprenyl diphosphate for example, inhibitors of 3-hydroxy-3-meth-ylglutaryl-coenzyme A reductase (HMG-CoA reductase), (2) compounds that prevent the recycling of polyprenyl diphosphate (bacitracin), and (3) compounds that prevent the phosphorylation of... 

For the study of polyprenyl glycosyl phosphates as intermediates in the synthesis of complex glycans, several techniques have been developed, and these have been described elsewhere in detail.18 20 Two important features should be emphasized. First, the very small amounts of polyprenyl phosphates that are present in most tissues for this reason, the use of radioactive techniques for the detection of products is obligatory. Second, on account of the hydrophobic nature of these compounds, and as the enzymes involved in the reactions are membrane-bound, the use of detergents and organic solvents becomes necessary. 

The polyprenols obtained from tobacco and Arum maculatum (solanesol and spadicol), which are all E, are the exceptions. Another interesting fact is that, in most seed-plants, the polyprenols are allylic, as is bacterial undecaprenol. Saturated or slightly modified polyprenols, such as animal dolichol, seem to be present only in fungi. Any of those plant polyprenols, in a phosphorylated form, can be potential sugar acceptors for transfer reactions. Experiments were performed with phosphorylated allylic polyprenols and membrane preparations from Phaseolus aureus. D-Mannose from GDP-D-mannose was incorporated into the exogenous, polyprenyl phosphates,29,49 52 but it was not possible to establish unequivocally the role of these polyprenols as lipid intermediates. 

The first evidence showing that plant polyprenols involved in glycosyl-transfer reactions are not allylic, but a-saturated, like animal dolichol (2), came from Pont Lezica and coworkers.23 The authors postulated that the presence of sugar acceptors having the properties of a-saturated polyprenyl phosphates may be a general feature of eukaryotic cells, in contrast to the a-unsaturated polyprenyl phosphates characteristic of prokaryotic cells. 

Further work in plant systems confirmed, by different methods (biosynthesis from mevalonate,27 28 mass spectrometry,33 and the techniques already mentioned30), that the polyprenyl phosphate involved in glycosyl-transfer reactions is dolichyl phosphate. Table II shows different sources from which dolichyl phosphate has been identified in plants. 

Another possible regulatory mechanism has been pointed out by Elbein for plant systems. His results implied either that the carrier lipid for different sugars are different polyprenyl phosphates, or that the glycosyltransferases have their own pools of lipid carriers, which do not mix.16 The results, compared to those for other plant and animal systems, suggested that the polyprenyl phosphates are the same for different sugars in each system, thus ruling out the first hypothesis, and reinforcing the concept of different pools.30... 

A. Kamino, K. Ariga, T. Kunitake, V. Birault, G. Pozzi, Y. Nakatani, G. Ourisson, Reinforcing Effect of Polyterpenoids on Polyprenyl Phosphate Monolayers , Colloid Surf., A, 103, 183 (1995)... 

K. Ariga, H. Yuki, J. Kikuchi, O. Dannenmuller, A.M. Albrecht-Gary, Y. Nakatani, G. Ourisson, Monolayer Studies of Single-Chain Polyprenyl Phosphates , Langmuir, 21,4578 (2005)... 

Could early membrane-forming amphiphiles have simply been polyprenyl phosphates, following the Strasbourg scenario (Birault et al., 1996) ... 

Are there automatic consequences of the self-organization of amphiphiles (such as polyprenyl phosphates) in water into membranes, and does this lead to novel properties Specifically, I consider the available evidence for the following features of membranes ... 

Specifically, polyprenyl phosphate vesicles form easily, provided that their lipophilic balance (the ratio of the lipophilic part to the hydrophilic part) is adequate. Single-chain polyprenyl phosphates require at least 20 carbons (geranylgeranyl, phytyl, or phytanyl phosphates). Double-chain polyprenyl phosphates require at least two C15 (famesyl) chains to generate vesicles, although this sometimes requires the help of a small amount of the corresponding free polyprenol (Pozzi et al., 1996) (see Figure 19.7.)... 

At present, polyprenyl phosphates, with ( -15 25 chains, are the simplest vesicle-fomiing phospholipids known, and they may have been the most primitive membrane constituents. We have been pleased to discover that the properties of vesicles... 

Furthermore, the head-groups of archaeal phospholipids are much too complex to be archaic, and I have postulated that polyprenyl phosphates might have been the most primitive membrane constituents. These phosphates can be biosynthesized by quite simple reactions, which, as we have shown, can be simulated in vitro from their C5 precursors (Desaubry et al., 2003). 

Tlie self-organization of amphiphiles (e.g. polyprenyl phosphates) in water leads to important consequences and to novel properties, such as the following. 

It makes possible a selective concentration of lipophiles in the membranes. Vesicles made of n-acyl lipids or of polyprenyl phosphates extract selectively into the membrane any lipophilic substance lipophilic pigments (Nile Red), cholesterol, polyprenols, carotenoids, etc. This is particularly important for those lipophilic substances that play a role in stabilizing the membrane cholesterol, hopanoids, polyprenols, and carotenoids (Bisseret et al., 1983 Milon et al., 1986 Lazrak et uZ.,1988 Krajewski-Bertrand et al., 1990). 

Birault, V., Pozzi, G., Plobeck, N. et al. (1996). Di(polyprenyl) phosphates as models for primitive membrane constituents synthesis and phase properties. Chemistry - a European Journal, 2, 789-99. 

Polyprenyl phosphates and pyrophosphates have been hydrolyzed by add and alkaline phosphatases (Table 13-6, entry 1). For this hydrolysis, classical chemical methods are inadequate as the reaction products decompose under add conditions 109]. 

The initiation reaction for O antigen subunit biosynthesis occurs at the interface of the plasma membrane and the cytosol where the nucleotide sugar precursors are available. The reaction involves the formation of a phosphodiester bond between a membrane-associated polyprenyl phosphate and a cytosolic UDP-sugar with the release of UMP. Depending on the specific microorganism, this reaction is catalyzed by two different... 

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