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MetaCyc Enzyme: Photosystem I iron-sulfur center

Gene: psaC Accession Number: CHRECP067 (MetaCyc)

Synonyms: ChreCp067

Species: Chlamydomonas reinhardtii

Component of:
photosystem I (extended summary available)
PS I-LHCI supercomplex (summary available)

Summary:
The chloroplast encoded gene psaC encodes a 2[4Fe-4S] bacterial ferredoxin type stromal subunit of photosystem I (PSI) [Fischer98a]. It binds the two terminal electron acceptors FA and FB which are both [4Fe-4S] proteins [Fischer98a][Fischer97]. The othermost iron-sulfur cluster of PsaC reduces soluble ferredoxin which binds to PSI via electrostatic interactions [Fischer99a].


MapMan: 1.1.2.2 PS.lightreaction.photosystem I.PSI polypeptide subunits
ProMEX peptides
Encoded in the chloroplast genome.

Citations: [Takahashi91a, Takahashi96, Maul02]

Locations: chloroplast

Map Position: [189,462 -> 189,707]

Molecular Weight of Polypeptide: 8.86 kD (from nucleotide sequence), 9.0 kD (experimental)

Unification Links: Entrez-gene:2717046 , Pride:Q00914 , Protein Model Portal:Q00914 , RefSeq:NP_958423.1 , SMR:Q00914 , UniProt:Q00914

Relationship Links: InterPro:IN-FAMILY:IPR001450 , InterPro:IN-FAMILY:IPR017491 , InterPro:IN-FAMILY:IPR017896 , InterPro:IN-FAMILY:IPR017900 , Pfam:IN-FAMILY:PF12838 , Prosite:IN-FAMILY:PS00198 , Prosite:IN-FAMILY:PS51379 , RefSeq:PART-OF:NC_005353.1

Gene-Reaction Schematic: ?

GO Terms:

Cellular Component: GO:0009507 - chloroplast

MultiFun Terms: metabolism energy production/transport

Credits:
Revised 04-May-2011 by Weerasinghe D


Enzymatic reaction of: ferredoxin oxidoreductase (Photosystem I iron-sulfur center)

EC Number: 1.97.1.12

a reduced plastocyanin + an oxidized ferredoxin + hν <=> an oxidized plastocyanin + a reduced ferredoxin

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the Enzyme Commission system.

The reaction is favored in the direction shown.

In Pathways: photosynthesis light reactions , hydrogen production VIII


Subunit of: photosystem I

Species: Chlamydomonas reinhardtii

Subunit composition of photosystem I = [PsaO][PsaN][PsaL][PsaK][PsaJ][PsaI][PsaH][PsaG][PsaF][PsaE][PsaD][PsaC][PsaB][PsaA]
         Photosystem I subunit O = PsaO (summary available)
         Photosystem I reaction center subunit N = PsaN (summary available)
         Photosystem I reaction center subunit XI = PsaL (summary available)
         Photosystem I reaction center subunit psaK = PsaK (summary available)
         Photosystem I reaction center subunit IX = PsaJ (summary available)
         Photosystem I reaction centre, subunit VIII = PsaI (summary available)
         Photosystem I reaction center subunit VI = PsaH (summary available)
         Photosystem I reaction center subunit V = PsaG (summary available)
         Photosystem I reaction center subunit III = PsaF (summary available)
         Photosystem I reaction center subunit IV = PsaE (summary available)
         Photosystem I reaction center subunit II = PsaD (summary available)
         Photosystem I iron-sulfur center = PsaC (summary available)
         Photosystem I P700 chlorophyll a apoprotein A2 = PsaB (summary available)
         Photosystem I P700 chlorophyll a apoprotein A1 = PsaA (summary available)

Component of: PS I-LHCI supercomplex (summary available)

Summary:
The function of PSI is to produce the NADPH necessary for the reduction of CO2 in the Calvin-Benson-Bassham cycle.

PSI is a multiprotein complex of up to 15 core subunits and is trimeric in cyanobacteria [Ozawa10]. In algae and higher plants the PSI core is associated with the peripheral light-harvesting antenna complex I (LHCI) that together form the PSI-LHCI supercomplex [Ozawa10]. PSI is associated with cofactors, such as chlorophyll, a, β carotene, lipid and iron sulfur clusters [Wicke11]. PSI uses solar energy to generate P700 [Webber01]. P700 is the primary electron donor that catalyzes electron transfer from plastocyanin or cytochrome c6 to the intermediate electron acceptors A0, A1 and FX [Sun99]. This culminates in the transfer of an electron to NADP+ to form NADPH via ferredoxin and the associated oxidoreductase.

P700 is a dimer of chlorophyll a and a' stabilized by PsaA and PsaB [Vassiliev95]. This forms the reaction center (RC) at the core of PSI. PsaF and PsaN are involved in docking plastocyanin or cytochrome c6 to the PSI complex and for efficient electron transfer to P700+ [Hippler97]. Two 4[FeS] clusters (FA and FB), the terminal electron acceptors bind to peripheral subunit PsaC, which together with PsaD and PsaE forms the docking site for ferredoxin to the PSI complex on the stromal side [Ozawa10].

PsaG, PsaH, and PsaN are special to eukaryotes and are involved in binding the light harvesting polypeptides. Some newly characterized accessory proteins Inner membrane ALBINO3-like protein 1 and Inner membrane ALBINO3-like protein 2 are crucial in mediating LHC protein integration into the thylakoid membrane [Gohre06].

Chaperone proteins that play a pivotal role in the stepwise integration of PSI subunits into a functional complex have recently been elucidated. These include chloroplast encoded Ycf4 and Ycf3, located in the thylakoid membrane that are required for a posttranslational step of PSI assembly [Albus10].

Credits:
Created 11-Jan-2010 by May P , MPI-MP
Revised 06-May-2011 by Weerasinghe D


Enzymatic reaction of: photosystem I

EC Number: 1.97.1.12

a reduced plastocyanin + an oxidized ferredoxin + hν <=> an oxidized plastocyanin + a reduced ferredoxin

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the Enzyme Commission system.

The reaction is favored in the direction shown.

In Pathways: photosynthesis light reactions , hydrogen production VIII


Enzymatic reaction of: photosystem I

2 NADP+[in] + 2 H+[in] + 4 e- <=> 2 NADPH[in]

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the direction of enzyme catalysis.

The reaction is favored in the direction shown.


Subunit of: PS I-LHCI supercomplex

Species: Chlamydomonas reinhardtii

Subunit composition of PS I-LHCI supercomplex = [(LHCA3)(LHCA2)][(LHCA4)(LHCA1)][(PsaO)(PsaN)(PsaL)(PsaK)(PsaJ)(PsaI)(PsaH)(PsaG)(PsaF)(PsaE)(PsaD)(PsaC)(PsaB)(PsaA)]
         LHCI-680 = (LHCA3)(LHCA2) (summary available)
                 Light-harvesting chlorophyll-a/b protein of photosystem I = LHCA3 (summary available)
                 Light-harvesting protein of photosystem I = LHCA2 (summary available)
         LHCI-705 = (LHCA4)(LHCA1) (summary available)
                 Light-harvesting protein of photosystem I = LHCA4 (summary available)
                 Light-harvesting protein of photosystem I = LHCA1 (summary available)
         photosystem I = (PsaO)(PsaN)(PsaL)(PsaK)(PsaJ)(PsaI)(PsaH)(PsaG)(PsaF)(PsaE)(PsaD)(PsaC)(PsaB)(PsaA) (extended summary available)
                 Photosystem I subunit O = PsaO (summary available)
                 Photosystem I reaction center subunit N = PsaN (summary available)
                 Photosystem I reaction center subunit XI = PsaL (summary available)
                 Photosystem I reaction center subunit psaK = PsaK (summary available)
                 Photosystem I reaction center subunit IX = PsaJ (summary available)
                 Photosystem I reaction centre, subunit VIII = PsaI (summary available)
                 Photosystem I reaction center subunit VI = PsaH (summary available)
                 Photosystem I reaction center subunit V = PsaG (summary available)
                 Photosystem I reaction center subunit III = PsaF (summary available)
                 Photosystem I reaction center subunit IV = PsaE (summary available)
                 Photosystem I reaction center subunit II = PsaD (summary available)
                 Photosystem I iron-sulfur center = PsaC (summary available)
                 Photosystem I P700 chlorophyll a apoprotein A2 = PsaB (summary available)
                 Photosystem I P700 chlorophyll a apoprotein A1 = PsaA (summary available)

Summary:
The core of the PS I-LHCI supercomplex is formed by the PsaA/B heterodimer with a few small subunits surrounding it, and this core contains all the components necessary for plastocyanin-ferredoxin oxidoreductase activity. All eukaryotic PSI cores characterized so far are monomers [Amunts07]. Except for a few chlorophylls required for the photochemistry, all chlorophylls bound in the core subunits function as light-harvesting pigments. Attached to the core are peripheral light-harvesting antennae composed of several LHCI proteins. Light energy captured by these light-harvesting chlorophylls is delivered to the P700 chlorophyll, where it is trapped as a stable charge separation. Chlamydomonas antenna is composed of LHCI-705 and LHCI-680 subcomplexes formed by Lhca1-4 polypeptides [Bassi92].

Citations: [Jun09]

Locations: chloroplast

GO Terms:

Cellular Component: GO:0009507 - chloroplast

Credits:
Created 12-Jan-2010 by May P , MPI-MP


References

Albus10: Albus CA, Ruf S, Schottler MA, Lein W, Kehr J, Bock R (2010). "Y3IP1, a nucleus-encoded thylakoid protein, cooperates with the plastid-encoded Ycf3 protein in photosystem I assembly of tobacco and Arabidopsis." Plant Cell 22(8);2838-55. PMID: 20807881

Amunts07: Amunts A, Drory O, Nelson N (2007). "The structure of a plant photosystem I supercomplex at 3.4 A resolution." Nature 447(7140);58-63. PMID: 17476261

Bassi92: Bassi R, Soen SY, Frank G, Zuber H, Rochaix JD (1992). "Characterization of chlorophyll a/b proteins of photosystem I from Chlamydomonas reinhardtii." J Biol Chem 267(36);25714-21. PMID: 1464588

Fischer97: Fischer N, Setif P, Rochaix JD (1997). "Targeted mutations in the psaC gene of Chlamydomonas reinhardtii: preferential reduction of FB at low temperature is not accompanied by altered electron flow from photosystem I to ferredoxin." Biochemistry 36(1);93-102. PMID: 8993322

Fischer98a: Fischer N, Hippler M, Setif P, Jacquot JP, Rochaix JD (1998). "The PsaC subunit of photosystem I provides an essential lysine residue for fast electron transfer to ferredoxin." EMBO J 17(4);849-58. PMID: 9463363

Fischer99a: Fischer N, Setif P, Rochaix JD (1999). "Site-directed mutagenesis of the PsaC subunit of photosystem I. F(b) is the cluster interacting with soluble ferredoxin." J Biol Chem 274(33);23333-40. PMID: 10438510

Gohre06: Gohre V, Ossenbuhl F, Crevecoeur M, Eichacker LA, Rochaix JD (2006). "One of two alb3 proteins is essential for the assembly of the photosystems and for cell survival in Chlamydomonas." Plant Cell 18(6);1454-66. PMID: 16679460

Grotjohann05: Grotjohann I, Fromme P (2005). "Structure of cyanobacterial photosystem I." Photosynth Res 85(1);51-72. PMID: 15977059

Hippler97: Hippler M, Drepper F, Farah J, Rochaix JD (1997). "Fast electron transfer from cytochrome c6 and plastocyanin to photosystem I of Chlamydomonas reinhardtii requires PsaF." Biochemistry 36(21);6343-9. PMID: 9174349

Jun09: Jun Minagawa (2009). "Light-Harvesting Proteins." Chapter 14. In: The Chlamydomonas Sourcebook. Second Edition.

Maul02: Maul JE, Lilly JW, Cui L, dePamphilis CW, Miller W, Harris EH, Stern DB (2002). "The Chlamydomonas reinhardtii plastid chromosome: islands of genes in a sea of repeats." Plant Cell 14(11);2659-79. PMID: 12417694

Ozawa10: Ozawa S, Onishi T, Takahashi Y (2010). "Identification and characterization of an assembly intermediate subcomplex of photosystem I in the green alga Chlamydomonas reinhardtii." J Biol Chem 285(26);20072-9. PMID: 20413595

Sun99: Sun J, Xu W, Hervas M, Navarro JA, Rosa MA, Chitnis PR (1999). "Oxidizing side of the cyanobacterial photosystem I. Evidence for interaction between the electron donor proteins and a luminal surface helix of the PsaB subunit." J Biol Chem 274(27);19048-54. PMID: 10383406

Takahashi91a: Takahashi Y, Goldschmidt-Clermont M, Soen SY, Franzen LG, Rochaix JD (1991). "Directed chloroplast transformation in Chlamydomonas reinhardtii: insertional inactivation of the psaC gene encoding the iron sulfur protein destabilizes photosystem I." EMBO J 10(8);2033-40. PMID: 1712288

Takahashi96: Takahashi Y, Rahire M, Breyton C, Popot JL, Joliot P, Rochaix JD (1996). "The chloroplast ycf7 (petL) open reading frame of Chlamydomonas reinhardtii encodes a small functionally important subunit of the cytochrome b6f complex." EMBO J 15(14);3498-506. PMID: 8670852

Vassiliev95: Vassiliev IR, Jung YS, Smart LB, Schulz R, McIntosh L, Golbeck JH (1995). "A mixed-ligand iron-sulfur cluster (C556SPaB or C565SPsaB) in the Fx-binding site leads to a decreased quantum efficiency of electron transfer in photosystem I." Biophys J 69(4);1544-53. PMID: 8534825

Webber01: Webber AN, Lubitz W (2001). "P700: the primary electron donor of photosystem I." Biochim Biophys Acta 1507(1-3);61-79. PMID: 11687208

Wicke11: Wicke S, Schneeweiss GM, dePamphilis CW, Muller KF, Quandt D (2011). "The evolution of the plastid chromosome in land plants: gene content, gene order, gene function." Plant Mol Biol 76(3-5);273-97. PMID: 21424877


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Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
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