Stoichiometric association of extrinsic cytochrome c550 and 12 kDa protein with a highly purified oxygen-evolving photosystem II core complex from Synechococcus vulcanus

Jian Ren Shen, Masahiko Ikeuchi, Yorinao Inoue

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116 Citations (Scopus)


A highly purified, native photosystem II (PS II) core complex was isolated from thylakoids of Synechococcus vulcanus, a thermophilic cyanobacterium by lauryldimethylamine N-oxide (LDAO) and dodecylβ-d-maltoside solubilization. This native PS II core complex contained, in addition to the proteins that have been well characterized in the core complex previously purified by LDAO and Triton X-100, two more extrinsic proteins with apparent molecular weights of 17 and 12 kDa. These two proteins were associated with the core complex in stoichiometric amounts and could be released by treatment with 1 M CaCl2 or 1 M alkaline Tris but not by 2 M NaCl or low-glycerol treatment, indicating that they are the real components of Ps II of this cyanobacterium. N-Terminal sequencing revealed that the 17 and 12 kDa proteins correspond to the apoprotein of cytochrome c550, a low potential c-type cytochrome, and the 9 kDa extrinsic protein previously found in a partially purified PS II preparation from Phormidium laminosum, respectively. In spite of retention of these two extrinsic proteins, no homologues of higher plant 23 and 17 kDa extrinsic proteins could be detected in this cyanobacterial PS II core complex.

Original languageEnglish
Pages (from-to)145-149
Number of pages5
JournalFEBS Letters
Issue number2
Publication statusPublished - Apr 20 1992
Externally publishedYes


  • Cytochrome c 9 kDa protein
  • Extrinsic protein
  • O evolution
  • Photosystem II
  • Synechococcus

ASJC Scopus subject areas

  • Biophysics
  • Structural Biology
  • Biochemistry
  • Molecular Biology
  • Genetics
  • Cell Biology


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