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Protein

Photosystem I P700 chlorophyll a apoprotein A2

Gene

psaB

Organism
Chlamydomonas reinhardtii (Chlamydomonas smithii)
Status
Reviewed-Annotation score: -Experimental evidence at protein leveli

Functioni

PsaA and PsaB bind P700, the primary electron donor of photosystem I (PSI), as well as the electron acceptors A0, A1 and FX. PSI is a plastocyanin/cytochrome c6-ferredoxin oxidoreductase, converting photonic excitation into a charge separation, which transfers an electron from the donor P700 chlorophyll pair to the spectroscopically characterized acceptors A0, A1, FX, FA and FB in turn. Oxidized P700 is reduced on the lumenal side of the thylakoid membrane by plastocyanin or cytochrome c6.
Both potential cofactor branches in PSI seem to be active; however, electron transfer seems to proceed preferentially down the path including the phylloquinone bound by PsaA.

Catalytic activityi

Reduced plastocyanin + oxidized ferredoxin + light = oxidized plastocyanin + reduced ferredoxin.

Cofactori

Note: P700 is a chlorophyll a/chlorophyll a' dimer, A0 is one or more chlorophyll a, A1 is one or both phylloquinones and FX is a shared 4Fe-4S iron-sulfur center.By similarity

Sites

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Metal bindingi560Iron-sulfur (4Fe-4S); shared with dimeric partner1
Metal bindingi569Iron-sulfur (4Fe-4S); shared with dimeric partnerBy similarity1
Metal bindingi655Magnesium (chlorophyll-a B1 axial ligand; P700 special pair)1
Metal bindingi663Magnesium (chlorophyll-a B3 axial ligand)By similarity1
Binding sitei671Chlorophyll-a B3By similarity1
Binding sitei672Phylloquinone B1

GO - Molecular functioni

GO - Biological processi

Keywordsi

Molecular functionOxidoreductase
Biological processElectron transport, Photosynthesis, Transport
Ligand4Fe-4S, Chlorophyll, Chromophore, Iron, Iron-sulfur, Magnesium, Metal-binding

Enzyme and pathway databases

BioCyciMetaCyc:CHRECP048-MONOMER
BRENDAi1.97.1.12 1318

Names & Taxonomyi

Protein namesi
Recommended name:
Photosystem I P700 chlorophyll a apoprotein A2 (EC:1.97.1.12)
Alternative name(s):
PSI-B
PsaB
Gene namesi
Name:psaB
Synonyms:ps1a2
Encoded oniPlastid; Chloroplast
OrganismiChlamydomonas reinhardtii (Chlamydomonas smithii)
Taxonomic identifieri3055 [NCBI]
Taxonomic lineageiEukaryotaViridiplantaeChlorophytaChlorophyceaeChlamydomonadalesChlamydomonadaceaeChlamydomonas
Proteomesi
  • UP000006906 Componenti: Chloroplast

Subcellular locationi

Extracellular region or secreted Cytosol Plasma membrane Cell wall Cytoskeleton Vacuole Chloroplast Endosome Peroxisome ER Golgi apparatus Nucleus Mitochondrion Manual annotation Automatic computational assertion Graphics by Christian Stolte; Source: COMPARTMENTS

Topology

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Transmembranei47 – 70Helical; Name=ISequence analysisAdd BLAST24
Transmembranei136 – 159Helical; Name=IISequence analysisAdd BLAST24
Transmembranei176 – 200Helical; Name=IIISequence analysisAdd BLAST25
Transmembranei274 – 292Helical; Name=IVSequence analysisAdd BLAST19
Transmembranei331 – 354Helical; Name=VSequence analysisAdd BLAST24
Transmembranei370 – 396Helical; Name=VISequence analysisAdd BLAST27
Transmembranei418 – 440Helical; Name=VIISequence analysisAdd BLAST23
Transmembranei518 – 536Helical; Name=VIIISequence analysisAdd BLAST19
Transmembranei576 – 597Helical; Name=IXSequence analysisAdd BLAST22
Transmembranei644 – 666Helical; Name=XSequence analysisAdd BLAST23
Transmembranei708 – 728Helical; Name=XISequence analysisAdd BLAST21

Keywords - Cellular componenti

Chloroplast, Membrane, Photosystem I, Plastid, Thylakoid

Pathology & Biotechi

Mutagenesis

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Mutagenesisi559P → A or L: Assembles functional PSI. Reaction center is somewhat unstable and interaction with psaC is impaired. The LEU mutant is less stable than the ALA mutant. 1 Publication1
Mutagenesisi560C → H: Loss of PSI assembly and function. 1 Publication1
Mutagenesisi561D → N: Loss of PSI assembly and function. 1 Publication1
Mutagenesisi563P → L: Assembles functional PSI. Reaction center is somewhat unstable and interaction with psaC is impaired. 1 Publication1
Mutagenesisi565R → E: Loss of PSI assembly and function. 1 Publication1
Mutagenesisi655H → C, G, N or S: Contains somewhat decreased amounts of PSI, depending on the strain; significantly changes the spin density of the P700+ cation radical. 2 Publications1
Mutagenesisi655H → D: Very little PSI detected. 2 Publications1
Mutagenesisi655H → F or L: Loss of P700 function. 2 Publications1
Mutagenesisi655H → Q: Impairment of P700 function. More severe; when associated with Q-676 in psaA. 2 Publications1
Mutagenesisi655H → R: No PSI detected. 2 Publications1
Mutagenesisi672W → F: Still able to photoaccumulate an electron on A1. 1

PTM / Processingi

Molecule processing

Feature keyPosition(s)DescriptionActionsGraphical viewLength
ChainiPRO_00000886091 – 735Photosystem I P700 chlorophyll a apoprotein A2Add BLAST735

Proteomic databases

PaxDbiP09144

Interactioni

Subunit structurei

The PsaA/B heterodimer binds the P700 chlorophyll special pair and subsequent electron acceptors. PSI consists of a core antenna complex that captures photons, and an electron transfer chain that converts photonic excitation into a charge separation. The eukaryotic PSI reaction center is composed of at least 11 subunits.

Protein-protein interaction databases

IntActiP09144, 4 interactors
STRINGi3055.DAA00949

Structurei

3D structure databases

ProteinModelPortaliP09144
SMRiP09144
ModBaseiSearch...
MobiDBiSearch...

Family & Domainsi

Sequence similaritiesi

Belongs to the PsaA/PsaB family.Curated

Keywords - Domaini

Transmembrane, Transmembrane helix

Phylogenomic databases

eggNOGiENOG410IE88 Eukaryota
ENOG410Y2QV LUCA
InParanoidiP09144
KOiK02690

Family and domain databases

Gene3Di1.20.1130.10, 1 hit
HAMAPiMF_00482 PSI_PsaB, 1 hit
InterProiView protein in InterPro
IPR001280 PSI_PsaA/B
IPR020586 PSI_PsaA/B_CS
IPR036408 PSI_PsaA/B_sf
IPR006244 PSI_PsaB
PfamiView protein in Pfam
PF00223 PsaA_PsaB, 1 hit
PIRSFiPIRSF002905 PSI_A, 1 hit
PRINTSiPR00257 PHOTSYSPSAAB
SUPFAMiSSF81558 SSF81558, 1 hit
TIGRFAMsiTIGR01336 psaB, 1 hit
PROSITEiView protein in PROSITE
PS00419 PHOTOSYSTEM_I_PSAAB, 1 hit

Sequencei

Sequence statusi: Complete.

P09144-1 [UniParc]FASTAAdd to basket

« Hide

        10         20         30         40         50
MATKLFPKFS QGLAQDPTTR RIWYGLAMAH DFESHDGMTE ENLYQKIFAS
60 70 80 90 100
HFGQLSIIFL WTSGNLFHVA WQGNFEQWVT DPVHIRPIAH AIWDPHFGQP
110 120 130 140 150
AVEAFTRGGA SGPVNISTSG VYQWWYTIGM RTNQDLYVGS VFLALVSAIF
160 170 180 190 200
LFAGWLHLQP NFQPSLSWFK DAESRLNHHL SGLFGVSSLA WTGHLVHVAI
210 220 230 240 250
PESRGQHVGW DNFLSVLPHP QGLTPFFTGN WAAYAQSPDT ASHVFGTAQG
260 270 280 290 300
SGQAILTFLG GFHPQTQSLW LTDMAHHHLA IAVIFIVAGH MYRTNFGIGH
310 320 330 340 350
RMQAILEAHT PPSGSLGAGH KGLFDTVNNS LHFQLGLALA SVGTITSLVA
360 370 380 390 400
QHMYSLPPYA FQAIDFTTQA ALYTHHQYIA GFIMCGAFAH GAIFFIRDYD
410 420 430 440 450
PEQNKGNVLA RMLDHKEALI SHLSWVSLFL GFHTLGLYVH NDVMQAFGTP
460 470 480 490 500
EKQILIEPVF AQWIQAAHGK ALYGFDFLLS SKTSAAFANG QSLWLPGWLD
510 520 530 540 550
AINNNQNSLF LTIGPGDFLV HHAIALGLHT TTLILVKGAL DARGSKLMPD
560 570 580 590 600
KKDFGYSFPC DGPGRGGTCD ISAYDAFYLA VFWMLNTIGW VTFYWHWKHL
610 620 630 640 650
TLWQGNVAQF DESSTYLMGW LRDYLWLNSS QLINGYNPFG MNSLSVWAWT
660 670 680 690 700
FLFGHLIYAT GFMFLISWRG YWQELIETLV WAHEKTPLAN LVYWKDKPVA
710 720 730
LSIVQARLVG LAHFSVGYIF TYAAFLIAST SGRFG
Length:735
Mass (Da):82,109
Last modified:March 28, 2003 - v4
Checksum:i82F9914CE07A7908
GO

Experimental Info

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Sequence conflicti15Q → R in CAA29287 (PubMed:16453785).Curated1
Sequence conflicti18T → A in CAA29287 (PubMed:16453785).Curated1
Sequence conflicti21R → I in CAA29287 (PubMed:16453785).Curated1
Sequence conflicti37 – 38GM → VW in CAA29287 (PubMed:16453785).Curated2
Sequence conflicti48 – 49FA → IS in CAA29287 (PubMed:16453785).Curated2
Sequence conflicti89A → C in CAA29287 (PubMed:16453785).Curated1
Sequence conflicti203S → LQ in CAA29287 (PubMed:16453785).Curated1
Sequence conflicti298I → N in CAA29287 (PubMed:16453785).Curated1
Sequence conflicti335L → I in CAA29287 (PubMed:16453785).Curated1
Sequence conflicti515P → L (PubMed:16453785).Curated1
Sequence conflicti515P → L (PubMed:6302265).Curated1

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
X05848 Genomic DNA Translation: CAA29287.1
U57326 Genomic DNA Translation: AAN78307.1
FJ423446 Genomic DNA Translation: ACJ50135.1
AB044470 Genomic DNA Translation: BAB18396.1
J01399 Genomic DNA No translation available.
S67792 Genomic DNA Translation: AAB20423.2
BK000554 Genomic DNA Translation: DAA00949.2
PIRiB28341
S18319
RefSeqiNP_958404.1, NC_005353.1

Genome annotation databases

EnsemblPlantsiDAA00949; DAA00949; DAA00949
GeneIDi2717038
GrameneiDAA00949; DAA00949; DAA00949
KEGGicre:ChreCp048

Entry informationi

Entry nameiPSAB_CHLRE
AccessioniPrimary (citable) accession number: P09144
Secondary accession number(s): B7U1I8
, Q36714, Q8HR52, Q9GH44
Entry historyiIntegrated into UniProtKB/Swiss-Prot: July 1, 1989
Last sequence update: March 28, 2003
Last modified: May 23, 2018
This is version 145 of the entry and version 4 of the sequence. See complete history.
Entry statusiReviewed (UniProtKB/Swiss-Prot)
Annotation programPlant Protein Annotation Program

Miscellaneousi

Keywords - Technical termi

Complete proteome, Reference proteome

Documents

  1. SIMILARITY comments
    Index of protein domains and families

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