Act as a stabilizer in the membrane bilayer. Even so, additional studies are required to establish the biophysical properties of such macromolecules and enlighten their attainable function in the bacterial outer membrane. In case of lipid A in 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 high ordering in 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 complex from oxidative damage (27). This may perhaps also hold true for Bradyrhizobium, which, in contrast to Rhizobium, are able to fix nitrogen also within the free-living state (non-symbiotically). Our research proved that the lipid A backbone of LPS from all examined strains had been composed of a D-GlcpN3N-disaccharide, substituted at CCR4 Antagonist custom synthesis position C-4 by an -D-Manp-(136)- -DManp disaccharide, whereas the position C-1 was occupied by -(131)-linked D-GalpA. The presence of D-GlcpN3N inside the lipid A backbone of the LPS of nitrogen-fixing bacteria is rather popular. This amino sugar was reported for lipid A with the LPS from Mesorhizobium loti (18, 43), M. huakuii (20), A. caulinodans (24), as well as other symbiotic bacteria belonging towards the genera Ochrobactrum and Phyllobacterium.three D-GlcpN3N was also discovered in lipid A derived from other, non-rhizobial bacteria, e.g. Bcl-2 Antagonist list Rhodopseudomonas (where the presence of this amino sugar was described for the initial time) (44), Thiobacillus sp. (45), pathogenic Brucella abortus (46), and Campylobacter jejuni (47), as well as in the hyperthermophilic bacterium Aquifex pyrophilus (48). Mannose-containing lipid A samples had been identified earlier in the predatory bacterium Bdellovibrio bacteriovorus, where mannose residues occupied positions C-1 and C-4 on the D-GlcpN3N-disaccharide (49), and in phototrophic bacterium Rhodomicrobium vannielli (50), in which the C-4 with the glucosaminyl disaccharide backbone was occupied by one particular mannose residue. Lately, we reported the presence of a neutral mannose-containing lipid A in LPS of B. elkanii USDA 76 (21). Within this bacterium it was demonstrated that two mannose residues forming a disaccharide had been linked to C-4 and one particular residue to C-1 from the D-GlcpN3N-disaccharide. In B. japonicum USDA 110 position C-1 with the lipid A backbone was substituted by an -(131)-linked D-GalpA. This distinctive substitution on the lipid A backbone had been noticedA. Choma, individual communication.35652 JOURNAL OF BIOLOGICAL CHEMISTRYVOLUME 289 ?Quantity 51 ?DECEMBER 19,Hopanoid-containing Lipid A of BradyrhizobiumTABLE 5 1 H and 13C NMR chemical shifts of fatty acids from B. japonicum lipid ANo. 1. Fatty acids signals Olefinic protons/carbons -CONH-HC CH-CONH-HC CH-CONH-CH2-CH2-HC CH-CONH-CH2-CH2-HC CH-CONHOlefinic protons/carbons (separated one particular double bound) -CH2-HC CH-CH2-HC CHIst ?3-OR )-FAa 1/ two CONH-Sug R-COO1.214 four. IInd ?(3-OR -FAa 1/ two -CONH-Sug R-COO5. Ist ?[( -1)-OR]c VLCFA -1 -2 -3 -4 and subsequent CH2 groups R(-COO-) from hopanoid 6. IInd ?[( -1)-OR]c VLCFA -1 -2 -3 R(-COO-) from 2nd hopanoid 7. (3-OH) FA with unsubstituted OH group 1/ 2 1.213 four.881 1.487; 1.588 1.308 20.03 72.070 36.340 25.67 172.00 43.81 68.88 ND ND 68.45 39.33 26.ten 67.61 33.19 26.ten 1.257 four.980 1.504; 1.623 1.338 1.450 20.03 73.21 36.14 25.85 28.91 172.82 2.413/2.525 5.1.