| Abstract |
ORF326, frxC and ORF469 of a transfomable cynobacterium, Synechcystis PCC6803, have sequence similarity with ORF465 on the choroplast genome of a livewort, Marchantia polymorpha, respectively. To elucidate their functions,targeted mutagenesis was performed by transformation with clened DNA in which the ORF was disrupted by insertion of a kanamycin resistancen gene cassette.Streak-purifications of a single colony of each transformant were repeatde to segregate homozygous mutants for disrupted copies, because Synechocystis PCC6803 was reported to have approximately 10 chromosomal DNA copies. Southern blot analysis revealed that mutants for ORF326 had not only disrupted ORF326 copies but also wild type ORF326 copies. This suggests that ORF326 is indispensable for growth under the mixotrophic growth condition used. However, mutants for frxC and mutants for ORF469 had only mutated copies, indicating that they dispensable for growth. Growth and chlorophyll a content of an ORF469-disrupted mutant were compared and chlorophyll a content of an ORF469-disrupted mutant were compared to those of wild type under mixotrophic growth condition, but no significant difference was detected. This indicates that ORF469 is required for neither normal growth nor chlorophyll biosynthesis under thie condition.
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