Isolation, characterization, and chromosomal mapping of an ftsZ gene from the unicellular primitive red alga Cyanidium caldarium RK-1

The FtsZ protein is involved in eukaryote plastid division, but there is li ttle information on its involvement in the plastid-dividing apparatus. To i nvestigate the relationship between FtsZ and the plastid-dividing ring, the ftsZ gene was isolated from the unicellular primitive red alga Cyanidium c aldarium RK-1. Comparison of several prokaryotic and eukaryotic FtsZ protei ns shows that there are six highly conserved domains in the core region of FtsZ. To determine the chromosomal location of ftsZ, we first determined th e electrophoretic karyotype of C. caldarium RK-1. Southern-hybridization an alysis combined with CHEF revealed the chromosomes on which the ftsZ gene e xist. Northern-hybridization analysis indicated that the C. caldarium RK-1 ftsZ gene is transcribed as a 1.9-kb molecule, and that the transcripts spe cifically accumulate just before plastid division. Phylogenetic analysis in dicated that C. caldarium RK-1 and other eukaryotic ftsZ genes are the desc endants of cyanobacterial ftsZ genes, supporting the current agreement that FtsZ is involved in plastid division.