Act as a stabilizer of the membrane bilayer. Nonetheless, more research are required to establish the biophysical properties of such macromolecules and enlighten their possible function in the bacterial outer membrane. In case of lipid A from the photosynthetic KDM3 Inhibitor custom synthesis Bradyrhizobium strain it was confirmed, by biophysical analysis of reconstituted asymmetric liposomes, that the architecture of this unusual lipid A was optimally suited to induce a higher ordering of the outer membrane, reinforcing its stability and rigidity (32). In addition, hopanoid lipids of nitrogen-fixing bacteria (Frankia) are proposed to kind a form of diffusion barrier to shield the oxygen-sensitive nitrogrenase-hydrogenase complex from oxidative damage (27). This might also hold accurate 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 were 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 within the lipid A backbone of the LPS of nitrogen-fixing bacteria is rather typical. This amino sugar was reported for lipid A on the LPS from Mesorhizobium loti (18, 43), M. huakuii (20), A. caulinodans (24), along with other symbiotic bacteria belonging to the genera Ochrobactrum and Phyllobacterium.3 D-GlcpN3N was also found in lipid A derived from other, non-rhizobial bacteria, e.g. Rhodopseudomonas (exactly where the presence of this amino sugar was described for the very first time) (44), Thiobacillus sp. (45), DPP-4 Inhibitor custom synthesis pathogenic Brucella abortus (46), and Campylobacter jejuni (47), as well as inside the hyperthermophilic bacterium Aquifex pyrophilus (48). Mannose-containing lipid A samples were identified earlier inside the predatory bacterium Bdellovibrio bacteriovorus, where mannose residues occupied positions C-1 and C-4 of the D-GlcpN3N-disaccharide (49), and in phototrophic bacterium Rhodomicrobium vannielli (50), in which the C-4 of the glucosaminyl disaccharide backbone was occupied by a single mannose residue. Recently, we reported the presence of a neutral mannose-containing lipid A in LPS of B. elkanii USDA 76 (21). In this bacterium it was demonstrated that two mannose residues forming a disaccharide were linked to C-4 and a single residue to C-1 on the D-GlcpN3N-disaccharide. In B. japonicum USDA 110 position C-1 of your lipid A backbone was substituted by an -(131)-linked D-GalpA. This special substitution of your lipid A backbone had been noticedA. Choma, private communication.35652 JOURNAL OF BIOLOGICAL CHEMISTRYVOLUME 289 ?Quantity 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/ 2 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 26.10 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.
