Act as a stabilizer in the membrane bilayer. Nevertheless, further studies are required to establish the biophysical properties of such macromolecules and enlighten their feasible function within 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 unusual lipid A was optimally suited to induce a higher ordering from the outer membrane, reinforcing its stability and rigidity (32). Additionally, hopanoid lipids of nitrogen-fixing bacteria (Frankia) are proposed to kind a sort of diffusion barrier to guard the oxygen-sensitive nitrogrenase-hydrogenase complicated from oxidative harm (27). This may perhaps also hold true for Bradyrhizobium, which, in contrast to Rhizobium, are capable to repair nitrogen also within the free-living state (non-symbiotically). Our studies proved that the lipid A backbone of LPS from all examined strains have been IL-10 Modulator supplier composed of a D-GlcpN3N-disaccharide, substituted at 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 in the lipid A backbone in the LPS of nitrogen-fixing bacteria is rather prevalent. This amino sugar was reported for lipid A in the LPS from Mesorhizobium loti (18, 43), M. huakuii (20), A. caulinodans (24), along with other symbiotic bacteria belonging HDAC11 Inhibitor Species towards the genera Ochrobactrum and Phyllobacterium.3 D-GlcpN3N was also located in lipid A derived from other, non-rhizobial bacteria, e.g. Rhodopseudomonas (exactly 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 inside the hyperthermophilic bacterium Aquifex pyrophilus (48). Mannose-containing lipid A samples have been identified earlier in the predatory bacterium Bdellovibrio bacteriovorus, exactly where mannose residues occupied positions C-1 and C-4 from the D-GlcpN3N-disaccharide (49), and in phototrophic bacterium Rhodomicrobium vannielli (50), in which the C-4 from the glucosaminyl disaccharide backbone was occupied by one 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 have been linked to C-4 and one residue to C-1 from the D-GlcpN3N-disaccharide. In B. japonicum USDA 110 position C-1 in the lipid A backbone was substituted by an -(131)-linked D-GalpA. This exclusive substitution on the lipid A backbone had been noticedA. Choma, personal communication.35652 JOURNAL OF BIOLOGICAL CHEMISTRYVOLUME 289 ?Number 51 ?DECEMBER 19,Hopanoid-containing Lipid A of BradyrhizobiumTABLE five 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 double bound) -CH2-HC CH-CH2-HC CHIst ?3-OR )-FAa 1/ two CONH-Sug R-COO1.214 4. IInd ?(3-OR -FAa 1/ 2 -CONH-Sug R-COO5. Ist ?[( -1)-OR]c VLCFA -1 -2 -3 -4 and subsequent CH2 groups R(-COO-) from hopanoid six. IInd ?[( -1)-OR]c VLCFA -1 -2 -3 R(-COO-) from 2nd hopanoid 7. (3-OH) FA with unsubstituted OH group 1/ two 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 26.10 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 two.413/2.525 5.1.