Isolation and functional reconstitution of a phosphate binding protein of the cyanobacterium Anacystis nidulans induced during phosphate-limited growth.

Adaptation of the blue-green algae Anacystis nidulans to phosphate-deficient growth leads to the expression of two membrane proteins, which appear as major constituents after separation by gel electrophoresis. One of these proteins, referred to as high affinity phosphate binding protein, has been isolated and its function reconstituted in liposomes. Partial sequencing showed no significant homologies to other proteins. The binding capacity of the proteoliposomes could be inhibited by arsenate but not by sulfhydryl reagents. Scatchard plot analyses of phosphate binding to reconstituted proteoliposomes suggested the existence of two different binding sites, one with a dissociation constant below micromolar and the other in the micromolar range.