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

Abstract

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