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-def icient 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 protein s. The binding capacity of the proteoliposomes could be inhibited by a rsenate but not by sulfhydryl reagents. Scatchard plot analyses of pho sphate binding to reconstituted proteoliposomes suggested the existenc e of two different binding sites, one with a dissociation constant bel ow micromolar and the other in the micromolar range.