2 research outputs found
Modulation of immune responses by targeting CD169/Siglec-1 with the glycan ligand
A fundamental role in the plant-bacterium interaction for
Gram-negative phytopathogenic bacteria is played by membrane
constituents, such as proteins, lipopoly- or lipooligosaccharides
(LPS, LOS) and Capsule Polysaccharides (CPS).
In the frame of the understanding the molecular basis of plant bacterium interaction, the Gram-negative bacterium Agrobacterium vitis was selected in this study. It is a phytopathogenic member of the Rhizobiaceae family and it induces the crown gall disease selectively on grapevines (Vitis vinifera).
A. vitis wild type strain F2/5, and its mutant in the quorum
sensing gene ÎaviR, were studied. The wild type produces biosurfactants; it is considered a model to study surface motility, and it causes necrosis on grapevine roots and HR (Hypersensitive
Response) on tobacco. Conversely, the mutant does not show any
surface motility and does not produce any surfactant material;
additionally, it induces neither necrosis on grape, nor HR on
tobacco. Therefore, the two strains were analyzed to shed some
light on the QS regulation of LOS structure and the consequent
variation, if any, on HR response. LOS from both strains were isolated and characterized: the two LOS structures maintained several common features and differed for few others.
With regards to the common patterns, firstly: the Lipid A region
was not phosphorylated at C4 of the non reducing glucosamine
but glycosylated by an uronic acid (GalA) unit, secondly: a third
Kdo and the rare Dha (3-deoxy-lyxo-2-heptulosaric acid) moiety
was present.
Importantly, the third Kdo and the Dha residues were substituted
by rhamnose in a not stoichiometric fashion, giving four different
oligosaccharide species.
The proportions among these four species, is the key difference
between the LOSs from both the two bacteria.
LOS from both strains and Lipid A from wild type A. vitis are
now examined for their HR potential in tobacco leaves and grapevine roots