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Research Paper

Isolation and characterization of a cyanobacterium-binding protein and its cell wall receptor in the lichen Peltigera canina

Eva-María Díaz, Mara Sacristán, María-Estrella Legaz and Carlos Vicente

Peltigera canina, a cyanolichen containing Nostoc as cyanobiont, produces and secretes arginase to a medium containing arginine. Secreted arginase acts as a lectin by binding to the surface of Nostoc cells through a specific receptor which develops urease activity. The enzyme urease has been located in the cell wall of recently isolated cyanobionts. Cytochemical detection of urease is achieved by producing a black, electron-dense precipitate of cobalt sulfide proceeding from CO2 evolved from urea hydrolysis in the presence of cobalt chloride. This urease has been pre-purified by affinity chromatography on a bead of active agarose to which arginase was attached. Urease was eluted from the beads by 50 mM α-D-galactose. The experimentally probed fact that a fungal lectin developing subsidiary arginase activity acts as a recognition factor of compatible algal cells in chlorolichens can now been expanded to cyanolichens.

Authors

Eva-María Díaz

Laboratory of Plant Physiology; The Lichen Team; Faculty of Biology; Complutense University; Madrid, Spain

Mara Sacristán

Laboratory of Plant Physiology; The Lichen Team; Faculty of Biology; Complutense University; Madrid, Spain

María-Estrella Legaz

Laboratory of Plant Physiology; The Lichen Team; Faculty of Biology; Complutense University; Madrid, Spain

Carlos Vicente Corresponding author: cvicente@bio.ucm.es

Laboratory of Plant Physiology; The Lichen Team; Faculty of Biology; Complutense University; Madrid, Spain