Bacterial membranes phospholipids

Telavancin is a new semisynthetic glycopeptide antibiotic with rapid bactericidal activity for gram-positive bacteria, which is mediated by a pair of biochemically distinct mechanisms inhibition of bacterial membrane phospholipids synthesis and inhibition of bacterial cell wall... 

Cyclopropane fatty acids occur frequently in bacterial membrane phospholipids. Also, they generally accompany the cyclopropene acids in seed oils (see following paragraph). Though other chain lengths have been reported, the most common cyclopropane acids are Cu and C19 (lactobacillic acid) compounds. They are probably formed from appropriate olefinic acids (16 1 9c and 18 111c) which are widely distributed in bacterial lipids. The cyclopropane acids have cis configuration but it is not clear whether they are individual enantiomers or racemic mixtures. 

In view of the fact that leaf lipids are dominated by those of the chloroplasts, it is worth emphasizing certain features of the latter s membranes. In contrast to mammalian and most bacterial membranes phospholipids are minor components. Phos-phatidylglycerol is the only phosphoglyceride of importance. About 75% of the acyl lipid content is glycosylglyceride (Table 3.215). In addition, the fatty acid composition of chloroplast acyl lipids is unusually rich in polyunsaturates. a-Linolenic acid, the main fatty acid, is particularly enriched in the two galactosylglycerides. Phosphatidylglycerol also con-... 

As mentioned above, phospholipids are abundant in eukaryotic and also bacterial membranes. Phospholipids are diesters of. vw-glycero-3-phosphoric acid as shown in Figure 3 for a variety of different lipid classes, all with the same palmi-toyl chain. 

Cytoplasmic membrane Polymyxins Polyenes Imidazoles and triazoles Naftidine Disrupt bacterial membranes Disrupt fungal membranes Inhibit ergosterol synthesis Inhibits ergosterol synthesis Bind to LPS and phospholipids Bind preferentially to ergosterol Pathway not in mammalian cells Pathway not in mammalian cells... 

WAP-8294A2 (JA-002) (157) Antibiotic WAP-8294A2(157) Antibacterial (MRSA infections and acne) Interacts selectively to membrane phospholipids, causing sever damage to bacterial membrane Various Phase I/II trials (gel, cream, injectable form) aRigen Pharmaceuticals 821-824... 

The major transition in membranes of log-phase cells is the broad gel to liquid-ciys-talline transition of the phospholipids that begins below 0 °C and ends at 20-24 °C. While observing the thermotropic transitions in bacterial membranes at stages of cell... 

The phospholipid bilayer is the basic structure of all biological membranes. In addition to the phospholipids noted above a variety of others exist. Thus cardiolipin (in which a glycerol diester links two phosphatidates) is present in mitochondrial and bacterial membranes. Sphingosine is an amphipathic lipid having the structure ... 

PC, the trivial name lecithin, is a neutral or zwitterionic phospholipid (Fig. 1). It is the most abundant phospholipid in animal tissues and the main component of nonchloroplast membranes in plants, where it amounts to about 50% of the total lipids. In bacterial membranes, PC is found in small quantities. PC is a useful bilayer component, which has a cylindrical shape and a net neutral charge (1). 

Aguilar, P.S., Cronan, J.E., Jr. and de Mendoza, D. A Bacillus subtilis gene induced by cold shock encodes a membrane phospholipid desaturase. J Bacterial, 180 (1998) 2194-2200. 

Fatty acids attached to membrane phospholipids can be post-synthetically converted to their cyclopropane derivatives during the stationary phase of bacterial growth. Their biosynthesis and function have been elucidated by the Cronan s laboratory (D.W. Grogan,... 

Additional work with closed vesicles derived from B. megaterium membranes demonstrates that NBD analogs of PE, PG, and PC can translocate across the membrane with a /i/2 of 30 s at 37°C (S. Hraffnsdottir, 1997). Similar types of experiments conducted with closed vesicles isolated from E. coli inner membrane reveal that NBD phospholipids traverse the bilayer with a of 7 min at 37°C (R. Huijbregts, 1996). This latter process is insensitive to protease and A-ethylmaleimide treatments and does not require ATP. Collectively, the data indicate that transbilayer lipid movement is rapid and does not require metabolic energy in bacterial membranes that harbor the biosynthetic enzymes for phospholipids. The basic characteristics of lipid translocation in the intact cell appear to be retained in isolated membranes. 

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