Pea chloroplast FtsZ can form multimers and correct the thermosensitive defect of an Escherichia coli ftsZ mutant

This paper reports the isolation and characterization of a cDNA encoding th e FtsZ protein of pea. The protein is synthesised as a precursor molecule o f 423 amino acids with a molecular mass of 44 kDa. When translated in vitro , the protein is translocated efficiently into isolated, intact pea chlorop lasts, demonstrating that the protein is localised in the chloroplast. Pea FtsZ synthesised in vitro formed multimers in a calcium-dependent manner. T he pea cDNA complemented the thermosensitive defect of an E. coli ftsZ muta nt in vivo and converted the filamentous phenotype of the E. coli mutant in to the normal wild-type morphology at 42 degrees C. However, pea FtsZ mutan ts that were defective in multimerisation in vitro failed to correct the ph enotype of the E. coli ftsZ mutant in vivo. The pea ftsZ transcripts were a bundantly present in the young leaves, but barely detectable in roots and s tems and undetectable in older leaves. Light stimulated transcription of th e gene significantly in young and dark-grown leaves. This study strongly su ggests that the division mechanisms used by chloroplasts and bacteria show considerable similarity.