Proteases are associated with a minor fucoxanthin chlorophyll a/c-binding protein from the diatom, Chaetoceros gracilis

Ryo Nagao, Tatsuya Tomo, Eri Noguchi, Takehiro Suzuki, Akinori Okumura, Rei Narikawa, Isao Enami, Masahiko Ikeuchi

Research output: Contribution to journalArticle

25 Citations (Scopus)

Abstract

We previously showed that most subunits in the oxygen-evolving photosystem II (PSII) preparation from the diatom Chaetoceros gracilis are proteolytically unstable. Here, we focused on identifying the proteases that cleave PSII subunits in thylakoid membranes. Major PSII subunits and fucoxanthin chlorophyll (Chl) a/c-binding proteins (FCPs) were specifically degraded in thylakoid membranes. The PSI subunits, PsaA and PsaB, were slowly degraded, and cytochrome f was barely degraded. Using zymography, proteolytic activities for three metalloproteases (116, 83, and 75 kDa) and one serine protease (156 kDa) were detected in thylakoid membranes. Two FCP fractions (FCP-A and FCP-B/C) and a photosystem fraction were separated by sucrose gradient centrifugation using dodecyl maltoside-solubilized thylakoids. The FCP-A fraction featured enriched Chl c compared with the bulk of FCP-B/C. Zymography revealed that 116, 83, and 94 kDa metalloproteases were mostly in the FCP-A fraction along with the 156 kDa serine protease. When solubilized thylakoids were separated with clear-native PAGE, zymography detected only the 83 kDa metalloprotease in the FCP-A band. Because FCP-A is selectively associated with PSII, these FCP-A-associated metalloproteases and serine protease may be responsible for the proteolytic degradation of FCPs and PSII in thylakoid membranes.

Original languageEnglish
Pages (from-to)2110-2117
Number of pages8
JournalBiochimica et Biophysica Acta - Bioenergetics
Volume1817
Issue number12
DOIs
Publication statusPublished - Dec 1 2012
Externally publishedYes

Keywords

  • FCP
  • Photosystem
  • Protease
  • Thylakoid

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Cell Biology

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