Pseudomonas aeruginosa lectins as a model for lectin production, properties, applications and functions.

Pseudomonas aeruginosa is one of the most troublesome human pathogens in the antibiotic consuming era. It produces lectins and lectinoid adhesins as secondary metabolites. The production of these compounds is genetically determined and is highly sensitive to changing environmental conditions. These dictate the type of the lectin produced ["type" variation], the lectin level ["on-off" variation], and its localization ["in-out" variation]. PA-I [galactophilic] and PA-II [fucose and mannose-binding] P. aeruginosa lectins are sensitive to EDTA and exhibit biophysical properties, resembling those of classical plant lectins. They exert similar in vitro biological effects and have an equal applicative potential. Lectin deficient strains and mutants of P. aeruginosa may be used for studies on lectin role in "conditioning" the bacterium lytic and toxic activities in its attacks on cells or macromolecules. The Pseudomonas lectins confunction with lytic and toxic activities: We suggest that they serve the homing and "condition" the lytic enzyme optimal activity on cellular and macromolecular targets. Namely their role resembles that of "positioning sites" of lytic enzymes and "receptor-binding" domains of powerful microbial, plant and animal toxic or lytic systems [including immunoglobulins, which "condition" the lytic activities of complement and phagocytes], as well as certain hormones, which condition limited key lytic activities, and thereby trigger a cascade of metabolic reactions.