Preliminary identification of a possible cell-division protein in the cyanobacterium Anacystis nidulans

Botanical Institute, P.O. Box 1045 and University of Oslo, Blindem, Oslo 3, Norway Zoological Institute, P.O. Box 1050, University of Oslo, Blindem, Oslo 3, Norway ABSTRACT SUMMARY: Cultures of the cyanobacterium Anacystis nidulans were grown under conditions of Mg 2+ -limitation and Mg 2+ -excess. Cell-free extracts, obtained after sonication and centrifugation (45000 g , 60 min), were analysed on polyacrylamide gels. Mg 2+ -limited cells, in which cell division was inhibited, accumulated a protein of molecular weight 50 x 10 3 . Only small amounts of this protein were detected in non-Mg 2+ -lirnited cultures. A protein of molecular weight 36 x 10 3 , found in non-Mg 2+ -limited cells, was not detected in Mg 2+ -limited cells. When a Mg 2+ shift-up from 5 µm to 1 mM was carried out in a chemostat, synthesis of the 36 x 103 protein was initiated and the amount of the 50 x 10 3 protein decreased whilst the main protein pattern remained unaltered. The possibility that the two proteins are involved in cell division is discussed.