Directed disruption of the Chlamydomonas chloroplast psbK gene destabilizes the photosystem II reaction center complex

Yuichiro Takahashi, Hideki Matsumoto, Michel Goldschmidt-Clermont, Jean David Rochaix

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Using particle gun-mediated chloroplast transformation we have disrupted the psbK gene of Chlamydomonas reihardtii with an aadA expression cassette that confers resistance to spectinomycin. The transformants are unable to grow photoautotrophically, but they grow normally in acetate-containing medium. They are deficient in photosystem II activity as measured by fluorescence transients and O2 evolution and they accumulate less than 10% of wild-type levels of photosystem II as measured by immunochemical means. Pulse-labeling experiments indicate that the photosystem II complex is synthesized normally in the transformants. These results differ from those obtained previously with similar cyanobacterial psbK mutants that were still capable of photoautotrophic growth (Ikeuchi et al., J. Biol. Chem. 266 (1991) 1111-1115). In C. reinhardtii the psbK product is required for the stable assembly and/or stability of the photosystem II complex and essential for photoautotrophic growth. The data also suggest that the stability requirements of the photosynthetic complexes differ considerably between C. reinhardtii and cyanobacteria.

Original languageEnglish
Pages (from-to)779-788
Number of pages10
JournalPlant Molecular Biology
Issue number5
Publication statusPublished - Mar 1 1994



  • Chlamydomonas reinhardtii
  • chloroplast
  • photosystem II
  • psbK
  • transformation

ASJC Scopus subject areas

  • Agronomy and Crop Science
  • Genetics
  • Plant Science

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