The binding of the pathogen ligand to the XA21 LRR-domain may result in dimerization and activation of intracellular kinase.
S. citri BR3-3X harbors a plasmid, pBJS-Original (pBJS-O), that encodes the spiroplasma adhesion related protein 1 (SaRproteinproteimplicatedted in binding of the pathogen to cells of its leafhopper vector, Circulifer tenellus.
Monocytes as well as type 1 macrophages (Mφ1) produce IL-23 in response to the binding of pathogens and pathogen-associated molecular patterns (PAMPs), such as lipopolysaccharide (LPS), to Toll-like receptors (TLRs) [5], [6].
This response is activated by components of the wall of invading micro-organisms, such as lipopolysaccharide (LPS) or peptidoglycan, following the binding of these pathogen-associated molecular patterns to pattern recognition receptors, such as the Toll-like receptors (TLRs) on tissue macrophages.
This can be induced by the binding of neisserial pathogens to the granulocyte-specific CEACAM3 followed by rapid stimulation of the GTPase Rac, eventually leading to phagocytosis and killing of the bacteria [ 20].
Interestingly, HMOs are produced by mothers not for direct nourishment of their infants, but instead have other biological functions such as inhibiting the binding of pathogens, stimulating the growth of commensal intestinal bacterial, and promoting postnatal brain development.
To define the precise structural features that determine the binding of distinct pathogens with CEACAMs, we have undertaken molecular modelling and mutation of the receptor molecules at previously implicated key target residues required for bacterial binding.
Milk oligosaccharides and glycoproteins have demonstrated protective qualities against enteric pathogen infections in infants by enhancing the binding of IgA with pathogens, having an antibacterial activity against pathogens and competing with pathogen binding sites [7], [8], [9].
These transgenic animals may serve as a model for the binding of human pathogens to human CEACAM1.
HMO share structural similarity with intestinal glycoconjugates and they prevent the binding of several pathogens to intestinal surfaces [47], [48], [49].
