SSF161029

Photosystem II reaction center protein T, PsbT

SUPERFAMILY entry
Member databaseSUPERFAMILY
SUPERFAMILY typehomologous superfamily

Description
Imported from IPR037268

Oxygenic photosynthesis uses two multi-subunit photosystems (I and II) located in the cell membranes of cyanobacteria and in the thylakoid membranes of chloroplasts in plants and algae. Photosystem II (PSII) has a P680 reaction centre containing chlorophyll 'a' that uses light energy to carry out the oxidation (splitting) of water molecules, and to produce ATP via a proton pump. Photosystem I (PSI) has a P700 reaction centre containing chlorophyll that takes the electron and associated hydrogen donated from PSII to reduce NADP+ to NADPH. Both ATP and NADPH are subsequently used in the light-independent reactions to convert carbon dioxide to glucose using the hydrogen atom extracted from water by PSII, releasing oxygen as a by-product
[6]
.

PSII is a multisubunit protein-pigment complex containing polypeptides both intrinsic and extrinsic to the photosynthetic membrane
[6, 1, 2, 5]
. Within the core of the complex, the chlorophyll and β-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 10kDa), and are involved in PSII assembly, stabilisation, dimerisation, and photo-protection
[4]
.

This entry represents the low molecular weight transmembrane protein PsbT found in PSII, which is thought to be associated with the D1 (PsbA) -D2 (PsbD) heterodimer. PsbT may be involved in the formation and/or stabilisation of dimeric PSII complexes, because in the absence of this protein dimeric PSII complexes were found to be less abundant. Furthermore, although PsbT does not confer photo-protection, it is required for the efficient recovery of photo-damaged PSII
[3]
.

References
Imported from IPR037268

1.Crystal structure of oxygen-evolving photosystem II from Thermosynechococcus vulcanus at 3.7-A resolution. Kamiya N, Shen JR. Proc. Natl. Acad. Sci. U.S.A. 100, 98-103, (2003). View articlePMID: 12518057

2.The evolutionary development of the protein complement of photosystem 2. Raymond J, Blankenship RE. Biochim. Biophys. Acta 1655, 133-9, (2004). PMID: 15100025

3.PsbT polypeptide is required for efficient repair of photodamaged photosystem II reaction center. Ohnishi N, Takahashi Y. J. Biol. Chem. 276, 33798-804, (2001). View articlePMID: 11451956

4.The low molecular mass subunits of the photosynthetic supracomplex, photosystem II. Shi LX, Schroder WP. Biochim. Biophys. Acta 1608, 75-96, (2004). PMID: 14871485

5.Thylakoid membrane lipid sulfoquinovosyl-diacylglycerol (SQDG) is required for full functioning of photosystem II in <i>Thermosynechococcus elongatus</i>. Nakajima Y, Umena Y, Nagao R, Endo K, Kobayashi K, Akita F, Suga M, Wada H, Noguchi T, Shen JR. J Biol Chem 293, 14786-14797, (2018). PMID: 30076221

6.Structural insights into photosystem II assembly. Zabret J, Bohn S, Schuller SK, Arnolds O, Moller M, Meier-Credo J, Liauw P, Chan A, Tajkhorshid E, Langer JD, Stoll R, Krieger-Liszkay A, Engel BD, Rudack T, Schuller JM, Nowaczyk MM. Nat Plants 7, 524-538, (2021). View articlePMID: 33846594

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