Rhizobium species strain NGR234 is the most promiscuous known rhizobium. In addition to the non-legume Parasponia andersonii, it nodulates at least 70 genera of legumes. Here we show that the nodulation genes of this bacterium determine the production of a large family of Nod-factors which are N-acylated chitin pentamers carrying a variety of substituents. The terminal non-reducing glucosamine is N-acylated with vaccenic or palmitic acids, is N-methylated, and carries varying numbers of carbamoyl groups. The reducing N-acetyl-glucosamine residue is substituted on position 6 with 2-O-methyl-L-fucose which may be acetylated or sulphated or non-substituted. All three internal residues are N-acetylated. At pico- to nanomolar concentrations, these signal molecules exhibit biological activities on the tropical legumes Macroptilium and Vigna (Phaseoleae), as well as on both the temperate genera Medicago (Trifoliae) and Vicia (Viciae). These data strongly suggest that the uniquely broad host range of NGR234 is mediated by the synthesis of a family of varied sulphated and non-sulphated lipo-oligosaccharide signals.

No abstract

Limited ~ubtihsin digestion of the tubulin ~, fl heterodlmei ha~ been used in this ~vork to reduce the total number of tubulin isotypes from 20 for native to 9 re1 bubtdma.¢lcaved tubuhn This indicalc~ that ~he major part of tul~uhn h,*terogenelty is located at the C.terminus of the molecule. The C-terminal pcpfides of both a and fl ~ubumt~ of tt,buhn ~.ere purified by anion-enchange HPLC. Combined tt~e of Edman desradation chemistry and mass spectrometry on the isolated peptlde~ shown that subtdi~in cleavase occurs at posmon Asp-438 and His-406 of ct and Gin-433 and His.396 o1"/3 tubuhn chums. Quaiahtat~ve analysis of our data show that cleavage at po~it~ons His.406 (~) and I-1is-396 (.8) occurs with a low efficient), an~l indicates that the naajor i~otylgeS of P~8 brain tubulm are modified by sequemial altachmeat of I to 5 glutam~c acid residues at posit~ons or -435 of ¢ and/3 tubuhn, respectively

New double-chain and gemini catanionic analogues of the glycolipid galβ1ceridentified as a cell receptor of the HIV-1 viruswere easily prepared in two steps from unprotected lactose. Due to their sugar moiety, these new catanionic surfactants were able to be cationized by sodium ions and therefore to be characterized in their monomeric forms by electrospray mass spectrometry. To our knowledge, this is the first time that catanionic surfactants have been directly observed, proving undoubtedly their existence as monomeric species. These new catanionic glycolipids showed interesting anti-HIV-1 activities, acting as monomeric analogues of galβ1cer. Finally, these new catanionic glycolipids were characterized by their surface active properties, by lamellar mesophases, and by their aptitude to spontaneously form vesicles.