Q0I910 · PSBA3_SYNS3

Function

function

Photosystem II (PSII) is a light-driven water:plastoquinone oxidoreductase that uses light energy to abstract electrons from H2O, generating O2 and a proton gradient subsequently used for ATP formation. It consists of a core antenna complex that captures photons, and an electron transfer chain that converts photonic excitation into a charge separation. The D1/D2 (PsbA/PsbD) reaction center heterodimer binds P680, the primary electron donor of PSII as well as several subsequent electron acceptors.

Miscellaneous

Cyanobacteria usually contain more than 2 copies of the psbA gene.
2 of the reaction center chlorophylls (ChlD1 and ChlD2) are entirely coordinated by water.
Herbicides such as atrazine, BNT, diuron or ioxynil bind in the Q(B) binding site and block subsequent electron transfer.

Catalytic activity

Cofactor

Note: The D1/D2 heterodimer binds P680, chlorophylls that are the primary electron donor of PSII, and subsequent electron acceptors. It shares a non-heme iron and each subunit binds pheophytin, quinone, additional chlorophylls, carotenoids and lipids. D1 provides most of the ligands for the Mn4-Ca-O5 cluster of the oxygen-evolving complex (OEC). There is also a Cl-1 ion associated with D1 and D2, which is required for oxygen evolution. The PSII complex binds additional chlorophylls, carotenoids and specific lipids.

Features

Showing features for binding site, site.

TypeIDPosition(s)Description
Binding site117Mg (UniProtKB | ChEBI) of chlorophyll a ChlzD1 (UniProtKB | ChEBI); axial binding residue
Binding site125pheophytin a D1 (UniProtKB | ChEBI)
Site160Tyrosine radical intermediate
Binding site169[CaMn4O5] cluster (UniProtKB | ChEBI)
Binding site188[CaMn4O5] cluster (UniProtKB | ChEBI)
Site189Stabilizes free radical intermediate
Binding site197Mg (UniProtKB | ChEBI) of chlorophyll a PD1 (UniProtKB | ChEBI); axial binding residue
Binding site214a quinone B (UniProtKB | ChEBI)
Binding site214Fe cation (UniProtKB | ChEBI); ligand shared with heterodimeric partner
Binding site263-264a quinone B (UniProtKB | ChEBI)
Binding site271Fe cation (UniProtKB | ChEBI); ligand shared with heterodimeric partner
Binding site331[CaMn4O5] cluster (UniProtKB | ChEBI)
Binding site332[CaMn4O5] cluster (UniProtKB | ChEBI)
Binding site341[CaMn4O5] cluster (UniProtKB | ChEBI)
Binding site343[CaMn4O5] cluster (UniProtKB | ChEBI)
Site343-344Cleavage; by CtpA

GO annotations

AspectTerm
Cellular Componentphotosystem II
Cellular Componentplasma membrane-derived thylakoid membrane
Molecular Functionchlorophyll binding
Molecular Functionelectron transporter, transferring electrons within the cyclic electron transport pathway of photosynthesis activity
Molecular Functioniron ion binding
Molecular Functionoxidoreductase activity, acting on diphenols and related substances as donors, oxygen as acceptor
Molecular Functionoxygen evolving activity
Biological Processphotosynthetic electron transport in photosystem II
Biological Processresponse to herbicide

Keywords

Enzyme and pathway databases

Names & Taxonomy

Protein names

  • Recommended name
    Photosystem II protein D1 3
  • EC number
  • Short names
    PSII D1 protein 3
  • Alternative names
    • Photosystem II Q(B) protein 3

Gene names

    • Name
      psbA3
    • Ordered locus names
      sync_1858

Organism names

Accessions

  • Primary accession
    Q0I910

Proteomes

Subcellular Location

Features

Showing features for transmembrane.

TypeIDPosition(s)Description
Transmembrane28-45Helical
Transmembrane117-132Helical
Transmembrane141-155Helical
Transmembrane196-217Helical
Transmembrane273-287Helical

Keywords

PTM/Processing

Features

Showing features for chain, propeptide.

TypeIDPosition(s)Description
ChainPRO_00003163901-343Photosystem II protein D1 3
PropeptidePRO_0000316391344-358

Post-translational modification

Tyr-160 forms a radical intermediate that is referred to as redox-active TyrZ, YZ or Y-Z.
C-terminally processed by CtpA; processing is essential to allow assembly of the oxygen-evolving complex and thus photosynthetic growth.

Interaction

Subunit

PSII is composed of 1 copy each of membrane proteins PsbA, PsbB, PsbC, PsbD, PsbE, PsbF, PsbH, PsbI, PsbJ, PsbK, PsbL, PsbM, PsbT, PsbX, PsbY, PsbZ, Psb30/Ycf12, peripheral proteins PsbO, CyanoQ (PsbQ), PsbU, PsbV and a large number of cofactors. It forms dimeric complexes.

Protein-protein interaction databases

Structure

Family & Domains

Sequence similarities

Belongs to the reaction center PufL/M/PsbA/D family.

Keywords

Phylogenomic databases

Family and domain databases

Sequence

  • Sequence status
    Complete
  • Sequence processing
    The displayed sequence is further processed into a mature form.
  • Length
    358
  • Mass (Da)
    39,375
  • Last updated
    2006-10-03 v1
  • Checksum
    9F35D58D9620F778
MATAVRSGRLSSWQSFCQWVTDTNNRIYIGWFGVLMIPCLLAATTCFIVAFIAAPPVDIDGIREPVAGSLLYGNNIISGAVVPSSNAIGLHFYPIWDAASLDEWLYNGGTYQLVVFHFLIGISAYMGRQWELSYRLGMRPWICVAYSAPLSAAMAVFLVYPFGQGSFSDGMPLGISGTFNFMLVFQAEHNILMHPFHMLGVAGVFGGSLFSAMHGSLVTSSLVRETTENESHNYGYKFGQEEETYNIVAAHGYFGRLIFQYASFNNSRSLHFLLGAWPVVGIWFTSMGVSTMAFNLNGFNFNQSILDSQGRVLNTWADMVNRAGLGMEVMHERNAHNFPLDLATVESTPVALQAPAIG

Keywords

Sequence databases

Nucleotide SequenceProtein SequenceMolecule TypeStatus
CP000435
EMBL· GenBank· DDBJ
ABI46741.1
EMBL· GenBank· DDBJ
Genomic DNA

Genome annotation databases

Similar Proteins

Disclaimer

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