NodFE-dependent fatty acids that lack an alpha-beta unsaturation are subject to differential transfer, leading to novel phospholipids.
In Rhizobium leguminosarum, the nodABC and nodFEL operons are involved in the production of lipo-chitin oligosaccharide signals that mediate host specificity. A nodFE-determined, highly unsaturated C18:4 fatty acid (trans-2, trans-4, trans-6, cis-11-octadecatetraenoic acid) is essential for the ability of the signals to induce nodule meristems and pre-infection thread structures on the host plant Vicia sativa. Of the nod genes, induction of only nodFE is sufficient to modify fatty acid biosynthesis to yield trans-2, trans-4, trans-6, cis-11-octadecatetraenoic acid, with an absorbance maximum of 303 nm. This unusual C18:4 fatty acid is not only found in the lipo-chitin oligosaccharides but is also associated with the phospholipids (O. Geiger, J. E. Thomas-Oates, J. Glushka, H. P. Spaink, and B. J. J. Lugtenberg, 1994, J. Biol. Chem. 269:11090-11097). Here we report that the phospholipids can contain other nodFE-derived fatty acids, a C18:3 trans-4, trans-6, cis-11-octadecatrienoic acid that has a characteristic absorption maximum at 225 nm, and a C18:2 octadecadienoic acid. Neither this C18:3 nor this C18:2 fatty acid has to date been observed attached to lipo-chitin oligosaccharides, suggesting that an as yet unknown acyl transferase (presumably NodA), responsible for the transfer of the fatty acyl chain to the glycan backbone of the lipo-chitin oligosaccharides, does not transfer all fatty acids synthesized by the action of NodFE to the lipo-chitin oligosaccharides. Rather, it must have a preference for alpha-beta unsaturated fatty acids during transfer.
Geiger
O
O
Institute of Molecular Plant Sciences, Leiden University, The Netherlands. geig1332@mailszrz.zrz.tu-berlin.de
Glushka
J
J
Lugtenberg
B J
BJ
Spaink
H P
HP
Thomas-Oates
J E
JE
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D005231:Fatty Acids, Unsaturated / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D015394:Molecular Structure; D009586:Nitrogen Fixation / Q000235:genetics; D010743:Phospholipids / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D016961:Rhizobium leguminosarum / Q000378:metabolism
D001426:Bacterial Proteins; D005231:Fatty Acids, Unsaturated; D010743:Phospholipids