title: Isolation and characterization of a cyanobacterium-binding protein and its cell wall receptor in the lichen Peltigera canina.
abstract: 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 CO(2) 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 alpha-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.affiliation: Laboratory of Plant Physiology, The Lichen Team, Faculty of Biology, Complutense University, Madrid, Spain.
authors.forename: Eva-María
authors.initials: EM
authors.lastname: Díaz
authors.forename: Mara
authors.initials: M
authors.lastname: Sacristán
authors.forename: María-Estrella
authors.initials: ME
authors.lastname: Legaz
authors.forename: Carlos
authors.initials: C
authors.lastname: Vicente
mesh_terms: D001119:Arginase / Q000378:metabolism; D002473:Cell Wall / Q000201:enzymology*; D000458:Cyanobacteria / Q000378:metabolism*; D005656:Fungal Proteins / Q000302:isolation & purification / Q000378:metabolism*; D037102:Lectins / Q000302:isolation & purification / Q000378:metabolism*; D008011:Lichens / Q000201:enzymology*; D014510:Urease / Q000378:metabolism
chemical_list: D005656:Fungal Proteins; D037102:Lectins; D014510:Urease; D001119:Arginase