Cloning And Characterization Of Dynamin-like FtsZ CDNA In Chlamydomonas Reinhardtii

Chloroplast and mitochondria probably arose by endosymbiosis of photosynthetic cyanobacterium and an alpha proteobacteria, respectively. Recent finding indicates that dynamin GTPase helps to divide animal and fungal mitochondria, and tubulin- like FtsZ GTPase, which is the essential component of the bacterial division machine, is involved in division of chloroplast and probably mitochondria of unicellular eukaryotes. The bacterial ancestor of mitochondria must have used FtsZ for division, but animal cells and yeast, which lack ftsZ gene through genomic sequencing, appear to have replaced FtsZ with dynaniin. Now, where the dynaniin come still keep a secret. Using degenerate oligodeoxyribonucleotide primer based on conserved regions of the cell-division protein FtsZ, a 570bp cDNA fragment, CrFtsZ, was isolated from chlamydomonas reinhardtii by RT-PCR. The fragment of CrFtsZ was added to 1 500bp by RACE approach. This fragment, which showed significant homology with other ftsZs, is a typical ftsZ gene, and encodes a protein with a long c-terminal. Southern blotting demonstrated there was only a single copy in chlamydomonas reinhardtli genome. Phylogenetic tree of 55 FtsZ homologies reconstructed based on 300 conserved amino acid regions of the cell-division protein FtsZ suggested that CrFtsZ was probably involved in division of mitochondria. C-terminal sequence analysis of CrFtsZ indicates that it has a few characters of dynaniin, such as a proline- rich c-temiinal and a propensity to interact with proteins containing Src-homology 3(SH3). Taken together, it is predicted that CrFtsZ may be the intermediate during the evolution from FtsZ to dynamin. Perhaps CrftsZ gradually lost the characteristics of FtsZ and became today抯 dynamin during the course of gene evolution. The gene CrFtsZ may be the missing link between FtsZ and dynamin in mitochondria and bacterial division.