DNA gyrase is involved in chloroplast nucleoid partitioning

Sun Cho Hye, Sook Lee Sang, Dong Kim Kwang, Inhwan Hwang, Jong Seok Lim, Youn Il Park, Hyun Sook Pai

Research output: Contribution to journalArticlepeer-review

55 Citations (Scopus)


DNA gyrase, which catalyzes topological transformation of DNA, plays an essential role in replication and transcription in prokaryotes. Virus-induced gene silencing of NbGyrA or NbGyrB, which putatively encode DNA gyrase subunits A and B, respectively, resulted in leaf yellowing phenotypes in Nicotiana benthamiana. NbGyrA and NbGyrB complemented the gyrA and gyrB temperature-sensitive mutations of Escherichia coli, respectively, which indicates that the plant and bacterial subunits are functionally similar. NbGyrA and NbGyrB were targeted to both chloroplasts and mitochondria, and depletion of these subunits affected both organelles by reducing chloroplast numbers and inducing morphological and physiological abnormalities in both organelles. Flow cytometry analysis revealed that the average DNA content in the affected chloroplasts and mitochondria was significantly higher than in the control organelles. Furthermore, 4′,6-diamidino-2-phenylindole staining revealed that the abnormal chloroplasts contained one or a few large nucleoids instead of multiple small nucleoids dispersed throughout the stroma. Pulse-field gel electrophoresis analyses of chloroplasts demonstrated that the sizes and/ or structure of the DNA molecules in the abnormal chloroplast nucleoids are highly aberrant. Based on these results, we propose that DNA gyrase plays a critical role in chloroplast nucleoid partitioning by regulating DNA topology.

Original languageEnglish
Pages (from-to)2665-2682
Number of pages18
JournalPlant Cell
Issue number10
Publication statusPublished - 2004 Oct

All Science Journal Classification (ASJC) codes

  • Plant Science
  • Cell Biology


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