CH3 -CH3 -CH3 -CH3 -CH3 -CH3 -CH3 -CH2 -CH2 -CH-OH -CH-OH
CH3 -CH3 -CH3 -CH3 -CH3 -CH3 -CH3 -CH2 -CH2 -CH-OH -CH-OH -COOR*a40.66 19.02 42.40 33.50 56.62 19.01 33.42 42.00 50.00 37.78 20.51 24.28 50.ten 41.90 33.98 23.27 55.06 44.73 41.99 28.06 46.45 37.22 33.61 21.73 16.16 16.86 16.70 16.28 20.58 32.51 28.52 73.99 74.94 172.R*, lipid A (-( -1)-OH-group).endosymbiotic conditions, e.g. Rhizobium, do not contain detectable amounts of triterpenoid lipids (28, 41). Diploptene, diplopterol, 2 -methyldiplopterol, aminobacteriohopanetriol, and adenosylhopane, accompanied by tetrahymanol and their methylated homologues: two -methyltetrahymanol, 20 -methyltetrahymanol, and two ,20 -dimethyltetrahymanol, were identified in cells of B. japonicum USDA 110 (28, 29). The hopanoid content in bradyrhizobial cells is generally higher, and in some strains accounts for a lot more than 40 of the total lipid fraction (28). Apart of their presence in bradyrhizobial cells, the 2-methylbacteriohopanepolyols are often KDM3 manufacturer located in cyanobacteria and are even proposed to be a biomarker of these prokaryotes (41, 42). Quite lately, the first hopanoid-containing lipid A, obtained from LPS of your photosynthetic Bradyrhizobium strain BTAi1, was mAChR1 custom synthesis structurally and functionally characterized (32). Within this lipid A, among the two ester-linked fatty acids was further substituted by a single hopanoid residue. In our perform we identified two hopanoid lipids, i.e. 34-carboxyl-bacteriohopane-32,33-diol and its methylated derivative 34-carboxyl-2 -methyl-bacteriohopane-32,33-diol. They have been present in LPS preparations obtained from B. japonicum, B. yuanmingense, and Bradyrhizobium sp. (Lupinus) strains. MS and NMR data proved that these hopanoid residues have been covalently linked towards the lipid A, forming a tertiary acyl substituent. The hydrophobic character of hopanoid rings collectively together with the presence of two hydroxyl groups inside the side chain, determined their unique position in the membrane. The VLCFAs, whichwere located to be components of all bradyrhizobial lipid A samples, contained between 26 and 34 carbon atoms, and have been present in mono- and dimethyl branched and straight forms. These fatty acids were components of two or, in case of B. yuanmingense lipid A, even three acyloxyacyl residues and could span the entire outer membrane. When one particular or two are also substituted by a hopanoid residue, their hydroxy groups could possibly be placed at the boundary in the double leaflet, whereas the hydrophobic rings may be hidden inside the membrane. As a result, the presence of such uncommon lipid A substituents is believed to possess a robust influence on the membrane properties and act as a stabilizer of the membrane bilayer. Having said that, more studies are needed to establish the biophysical properties of such macromolecules and enlighten their attainable function in the bacterial outer membrane. In case of lipid A from the photosynthetic Bradyrhizobium strain it was verified, by biophysical evaluation of reconstituted asymmetric liposomes, that the architecture of this uncommon lipid A was optimally suited to induce a higher ordering of the outer membrane, reinforcing its stability and rigidity (32). Moreover, hopanoid lipids of nitrogen-fixing bacteria (Frankia) are proposed to type a sort of diffusion barrier to guard the oxygen-sensitive nitrogrenase-hydrogenase complicated from oxidative damage (27). This may possibly also hold true for Bradyrhizobium, which, in contrast to Rhizobium, are in a position to repair nitrogen also inside the free-living state (non-symbiotically). Our studies proved that the lip.