Cytochrome b559

From Wikipedia, the free encyclopedia

Cytochrome b559, alpha (gene psbE) and beta (gene psbF)subunits
Identifiers
Symbol Cytochrom_B559
Pfam PF00283
InterPro IPR013081
PROSITE PDOC00464
OPM family 2
OPM protein 2axt
Available PDB structures:

1s5lF:7-35 2axtf:7-35
Lumenal portion of Cytochrome b559, alpha (gene psbE) subunit
Identifiers
Symbol Cytochrom_B559a
Pfam PF00284
InterPro IPR013082
PROSITE PDOC00464
SCOP 2axt
OPM family 2
OPM protein 2axt
Available PDB structures:

1s5le:42-81 2axte:42-81

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 (IPR013082), while in the beta subunit it occurs on its own.

[edit] References

  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. doi:10.1073/pnas.0135651100. 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. doi:10.1016/j.bbabio.2003.10.015. 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. doi:10.1016/j.bbabio.2003.12.004. PMID 14871485. 
  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. doi:10.1016/S0014-5793(02)03895-4. PMID 12560096. 
 This membrane protein-related article is a stub. You can help Wikipedia by expanding it.