A novel 3.5 kDa protein component of cyanobacterial photosystem I complexes

Masahiko Ikeuchi, Kintake Sonoike, Hiroyuki Koike, Himadri B. Pakrasi, Yorinao Inoue

Research output: Contribution to journalArticlepeer-review


A novel protein component of 3.5 kDa was detected in photosystem I complexes prepared from several cyanobacteria, viz. Synechococcus vulcanus, Synechococcus elongotus BP-1, Synechococcus sp. FCC 7002 and Synechocystis sp. FCC 6803. The complete amino acid sequence of this component was determined by direct protein sequencing. The sequences of the 3.5 kDa proteins from these four organisms were highly homologous to each other, featuring a hydrophobic domain in the middle. The cyanobacterial consensus sequence exhibits significant homology to the presumed product of ORF32 in the chloroplast DNA of liverwort (Marchantia polymorpha), but no homologous ORF is present in the chloroplast DNA of tobacco or rice. Since this protein appears to interact strongly with the PS I reaction center complex, it may play some role in the function and maintenance of the structure of PS I.

Original languageEnglish
Pages (from-to)1057-1063
Number of pages7
JournalPlant and Cell Physiology
Issue number8
StatePublished - Dec 1992


  • Cyanobacteria
  • Photosystem I
  • PsaM
  • Synecho coccus elongatus
  • Synechococcus sp. PCC 7002
  • Synechococcus vulcanus
  • Synechocystis sp. PCC 6803


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