Cytochrome b559

Jump to navigation Jump to search
Cytochrome b559, alpha (gene psbE) and beta (gene psbF)subunits
OPM superfamily2
OPM protein2axt
Lumenal portion of Cytochrome b559, alpha (gene psbE) subunit
OPM superfamily2
OPM protein2axt

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]


Cytochrome b559 is an important component of Photosystem II.

PSII is a multisubunit protein-pigment complex containing polypeptides both intrinsic and extrinsic to the photosynthetic membrane[1][2]. Within the core of the complex, the chlorophyll and beta-carotene pigments are mainly bound to the antenna proteins CP43 (PsbC) and CP47 (PsbB), which pass the excitation energy on to the reaction centre proteins D1 (Qb, PsbA) and D2 (Qa, PsbD) that bind all the redox-active cofactors involved in the energy conversion process. The PSII oxygen-evolving complex (OEC) oxidises water to provide protons for use by PSI, and consists of OEE1 (PsbO), OEE2 (PsbP) and OEE3 (PsbQ). The remaining subunits in PSII are of low molecular weight (less than 10 kDa), and are involved in PSII assembly, stabilisation, dimerisation, and photo-protection[3].

Cytochrome b559, which forms part of the reaction centre core of PSII is a heterodimer composed of one alpha subunit (PsbE), one beta (PsbF) subunit, and a haem cofactor. Two histidine residues from each subunit coordinate the haem. Although cytochrome b559 is a redox-active protein, it is unlikely to be involved in the primary electron transport in PSII due to its very slow photo-oxidation and photo-reduction kinetics. Instead, cytochrome b559 could participate in a secondary electron transport pathway that helps protect PSII from photo-damage. Cytochrome b559 is essential for PSII assembly[4].

This domain occurs in both the alpha and beta subunits of cytochrome B559. In the alpha sbunit it occurs together with a lumenal domain (InterPro: IPR013082), while in the beta subunit it occurs on its own.


  1. Kamiya N, Shen JR (2003). "Crystal structure of oxygen-evolving photosystem II from Thermosynechococcus vulcanus at 3.7-A resolution". Proc. Natl. Acad. Sci. U.S.A. 100 (1): 98–103. PMID 12518057.
  2. Blankenship RE, Raymond J (2004). "The evolutionary development of the protein complement of photosystem 2". Biochim. Biophys. Acta. 1655 (1–3): 133–139. PMID 15100025.
  3. Schroder WP, Shi LX (2004). "The low molecular mass subunits of the photosynthetic supracomplex, photosystem II". Biochim. Biophys. Acta. 1608 (2–3): 75–96. PMID 14871485. line feed character in |title= at position 54 (help)
  4. Burda K, Kruk J, Borgstadt R, Stanek J, StrzaBka K, Schmid GH, Kruse O (2003). "Mössbauer studies of the non-heme iron and cytochrome b559 in a Chlamydomonas reinhardtii PSI- mutant and their interactions with alpha-tocopherol quinone". FEBS Lett. 535 (1–3): 159–165. PMID 12560096.

Template:WikiDoc Sources