9LZJ: Photosystem I P700 chlorophyll a apoprotein A1
The PSI3-IsiA43 complex with a closed double ring of IsiA proteins bound to a trimeric PSI core. Determined by electron microscopy at 3.4 Å resolution. Released 31 Dec 2025.
- Method
- Electron microscopy
- Resolution
- 3.4 Å
- Organism
- Thermosynechococcus vestitus BP-1
- Chains
- 79
- Atoms
- 235,011
- Mol. weight
- 3566.28 kDa
- Ligands
- CLA, PQN, SF4, BCR
- Released
- 31 Dec 2025
Explore 9LZJ in 3D
Show helices and sheets
RCSB PDB
PDBe
Secondary structure: helices and β-sheets
9LZJ contains 1,109 α-helices and 477 β-strands across 79 chains. Residue ranges use author residue numbering, as in the PDB file, from PDBe. To see them in 3D, choose the Cartoon representation with Secondary structure coloring: helices, sheets and coils get different colors.
Chain a: 17 helices, 7 β-strands
| Element | Residues | Length | Sheet |
|---|
| α-helix | 24-26 | 3 | |
| α-helix | 28-33 | 6 | |
| α-helix | 39-66 | 28 | |
| α-helix | 82-88 | 7 | |
| β-strand | 92 | 1 | 85 |
| β-strand | 94 | 1 | 86 |
| β-strand | 98 | 1 | 85 |
| α-helix | 102-127 | 26 | |
| α-helix | 139-143 | 5 | |
| α-helix | 150-176 | 27 | |
| β-strand | 181-183 | 3 | 86 |
| β-strand | 188-190 | 3 | 86 |
| α-helix | 199-204 | 6 | |
| α-helix | 215-238 | 24 | |
| α-helix | 240-241 | 2 | |
| α-helix | 243-248 | 6 | |
| α-helix | 253-277 | 25 | |
| α-helix | 284-287 | 4 | |
| α-helix | 290-291 | 2 | |
| β-strand | 292-295 | 4 | 87 |
| β-strand | 299-302 | 4 | 87 |
| α-helix | 308-310 | 3 | |
| α-helix | 314-341 | 28 | |
| α-helix | 345-352 | 8 | |
Chain a1: 17 helices, 7 β-strands
| Element | Residues | Length | Sheet |
|---|
| α-helix | 28-33 | 6 | |
| α-helix | 39-66 | 28 | |
| α-helix | 82-87 | 6 | |
| β-strand | 92 | 1 | 98 |
| β-strand | 94 | 1 | 99 |
| β-strand | 98 | 1 | 98 |
| α-helix | 102-123 | 22 | |
| α-helix | 124-128 | 5 | |
| α-helix | 140-143 | 4 | |
| α-helix | 150-176 | 27 | |
| β-strand | 181-183 | 3 | 99 |
| β-strand | 188-190 | 3 | 99 |
| α-helix | 199-203 | 5 | |
| α-helix | 204-206 | 3 | |
| α-helix | 215-238 | 24 | |
| α-helix | 240-242 | 3 | |
| α-helix | 243-248 | 6 | |
| α-helix | 253-277 | 25 | |
| α-helix | 284-287 | 4 | |
| β-strand | 292-295 | 4 | 100 |
| β-strand | 299-302 | 4 | 100 |
| α-helix | 308-310 | 3 | |
| α-helix | 314-341 | 28 | |
| α-helix | 348-350 | 3 | |
Chain a2: 18 helices, 6 β-strands
| Element | Residues | Length | Sheet |
|---|
| α-helix | 28-37 | 10 | |
| α-helix | 39-66 | 28 | |
| α-helix | 82-87 | 6 | |
| β-strand | 92 | 1 | 106 |
| β-strand | 98 | 1 | 106 |
| α-helix | 102-123 | 22 | |
| α-helix | 124-128 | 5 | |
| α-helix | 139-142 | 4 | |
| α-helix | 150-176 | 27 | |
| β-strand | 181-183 | 3 | 107 |
| β-strand | 188-190 | 3 | 107 |
| α-helix | 199-203 | 5 | |
| α-helix | 204-206 | 3 | |
| α-helix | 215-238 | 24 | |
| α-helix | 240-241 | 2 | |
| α-helix | 243-248 | 6 | |
| α-helix | 253-277 | 25 | |
| α-helix | 290-291 | 2 | |
| β-strand | 292-295 | 4 | 108 |
| β-strand | 299-302 | 4 | 108 |
| α-helix | 308-310 | 3 | |
| α-helix | 311-313 | 3 | |
| α-helix | 314-341 | 28 | |
| α-helix | 347-350 | 4 | |
Chain a3: 18 helices, 7 β-strands
| Element | Residues | Length | Sheet |
|---|
| α-helix | 28-35 | 8 | |
| α-helix | 39-66 | 28 | |
| α-helix | 82-87 | 6 | |
| β-strand | 92 | 1 | 116 |
| β-strand | 94 | 1 | 117 |
| β-strand | 98 | 1 | 116 |
| α-helix | 102-123 | 22 | |
| α-helix | 124-128 | 5 | |
| α-helix | 139-142 | 4 | |
| α-helix | 150-176 | 27 | |
| β-strand | 181-183 | 3 | 117 |
| β-strand | 188-190 | 3 | 117 |
| α-helix | 199-203 | 5 | |
| α-helix | 204-206 | 3 | |
| α-helix | 215-238 | 24 | |
| α-helix | 240-242 | 3 | |
| α-helix | 243-248 | 6 | |
| α-helix | 253-277 | 25 | |
| α-helix | 284-287 | 4 | |
| α-helix | 290-291 | 2 | |
| β-strand | 292-295 | 4 | 118 |
| β-strand | 299-302 | 4 | 118 |
| α-helix | 308-310 | 3 | |
| α-helix | 314-341 | 28 | |
| α-helix | 346-351 | 6 | |
Chain a4: 17 helices, 7 β-strands
| Element | Residues | Length | Sheet |
|---|
| α-helix | 28-33 | 6 | |
| α-helix | 39-66 | 28 | |
| α-helix | 82-88 | 7 | |
| β-strand | 92 | 1 | 123 |
| β-strand | 94 | 1 | 124 |
| β-strand | 98 | 1 | 123 |
| α-helix | 102-123 | 22 | |
| α-helix | 124-128 | 5 | |
| α-helix | 139-143 | 5 | |
| α-helix | 150-176 | 27 | |
| β-strand | 181-183 | 3 | 124 |
| β-strand | 188-190 | 3 | 124 |
| α-helix | 199-204 | 6 | |
| α-helix | 215-238 | 24 | |
| α-helix | 240-242 | 3 | |
| α-helix | 243-248 | 6 | |
| α-helix | 253-277 | 25 | |
| α-helix | 284-287 | 4 | |
| α-helix | 290-291 | 2 | |
| β-strand | 292-295 | 4 | 125 |
| β-strand | 299-302 | 4 | 125 |
| α-helix | 308-310 | 3 | |
| α-helix | 314-340 | 27 | |
| α-helix | 345-347 | 3 | |
Chain a5: 17 helices, 7 β-strands
| Element | Residues | Length | Sheet |
|---|
| α-helix | 28-36 | 9 | |
| α-helix | 39-66 | 28 | |
| α-helix | 82-88 | 7 | |
| β-strand | 92 | 1 | 130 |
| β-strand | 94 | 1 | 131 |
| β-strand | 98 | 1 | 130 |
| α-helix | 102-123 | 22 | |
| α-helix | 124-128 | 5 | |
| α-helix | 139-143 | 5 | |
| α-helix | 150-176 | 27 | |
| β-strand | 181-183 | 3 | 131 |
| β-strand | 188-190 | 3 | 131 |
| α-helix | 199-203 | 5 | |
| α-helix | 204-206 | 3 | |
| α-helix | 215-238 | 24 | |
| α-helix | 240-242 | 3 | |
| α-helix | 243-248 | 6 | |
| α-helix | 253-277 | 25 | |
| α-helix | 284-287 | 4 | |
| α-helix | 290-291 | 2 | |
| β-strand | 292-295 | 4 | 132 |
| β-strand | 299-302 | 4 | 132 |
| α-helix | 314-340 | 27 | |
| α-helix | 347-351 | 5 | |
Chain a6: 15 helices, 7 β-strands
| Element | Residues | Length | Sheet |
|---|
| α-helix | 28-33 | 6 | |
| α-helix | 39-67 | 29 | |
| α-helix | 82-88 | 7 | |
| β-strand | 92 | 1 | 136 |
| β-strand | 94 | 1 | 137 |
| β-strand | 98 | 1 | 136 |
| α-helix | 102-123 | 22 | |
| α-helix | 124-128 | 5 | |
| α-helix | 138-141 | 4 | |
| α-helix | 150-176 | 27 | |
| β-strand | 181-183 | 3 | 137 |
| β-strand | 188-190 | 3 | 137 |
| α-helix | 199-203 | 5 | |
| α-helix | 215-238 | 24 | |
| α-helix | 240-242 | 3 | |
| α-helix | 243-248 | 6 | |
| α-helix | 253-277 | 25 | |
| α-helix | 290-291 | 2 | |
| β-strand | 292-295 | 4 | 138 |
| β-strand | 299-302 | 4 | 138 |
| α-helix | 314-341 | 28 | |
| α-helix | 346-349 | 4 | |
Chain aA: 48 helices, 19 β-strands
| Element | Residues | Length | Sheet |
|---|
| β-strand | 16-18 | 3 | 1 |
| α-helix | 27-29 | 3 | |
| α-helix | 37-40 | 4 | |
| β-strand | 44 | 1 | 2 |
| α-helix | 46-53 | 8 | |
| α-helix | 58-61 | 4 | |
| α-helix | 65-96 | 32 | |
| β-strand | 98 | 1 | 3 |
| α-helix | 100-105 | 6 | |
| α-helix | 111-112 | 2 | |
| β-strand | 113-114 | 2 | 3 |
| α-helix | 123-126 | 4 | |
| β-strand | 128-129 | 2 | 4 |
| β-strand | 135-136 | 2 | 4 |
| β-strand | 137-138 | 2 | 3 |
| α-helix | 143-150 | 8 | |
| α-helix | 155-177 | 23 | |
| α-helix | 178-182 | 5 | |
| β-strand | 183-185 | 3 | 1 |
| α-helix | 187-190 | 4 | |
| α-helix | 193-198 | 6 | |
| α-helix | 199-206 | 8 | |
| α-helix | 207-215 | 9 | |
| α-helix | 216-220 | 5 | |
| α-helix | 221-229 | 9 | |
| α-helix | 237-238 | 2 | |
| α-helix | 241-244 | 4 | |
| α-helix | 246-251 | 6 | |
| α-helix | 265-268 | 4 | |
| α-helix | 272-275 | 4 | |
| α-helix | 294-312 | 19 | |
| β-strand | 315 | 1 | 5 |
| β-strand | 323 | 1 | 5 |
| α-helix | 325-331 | 7 | |
| α-helix | 344-348 | 5 | |
| α-helix | 352-374 | 23 | |
| α-helix | 387-414 | 28 | |
| α-helix | 415-419 | 5 | |
| α-helix | 429-435 | 7 | |
| α-helix | 437-451 | 15 | |
| α-helix | 452-456 | 5 | |
| α-helix | 457-467 | 11 | |
| α-helix | 471-473 | 3 | |
| α-helix | 485-495 | 11 | |
| β-strand | 498 | 1 | 6 |
| β-strand | 502 | 1 | 6 |
| β-strand | 518-520 | 3 | 7 |
| β-strand | 523-526 | 4 | 7 |
| α-helix | 528-531 | 4 | |
| α-helix | 533-558 | 26 | |
| α-helix | 569-572 | 4 | |
| β-strand | 578 | 1 | 8 |
| β-strand | 587 | 1 | 8 |
| α-helix | 591-616 | 26 | |
| α-helix | 617-621 | 5 | |
| β-strand | 623-625 | 3 | 7 |
| β-strand | 631-633 | 3 | 7 |
| α-helix | 639-642 | 4 | |
| α-helix | 646-648 | 3 | |
| α-helix | 649-655 | 7 | |
| α-helix | 656-657 | 2 | |
| α-helix | 659-662 | 4 | |
| α-helix | 670-691 | 22 | |
| α-helix | 694-710 | 17 | |
| β-strand | 718 | 1 | 2 |
| α-helix | 721-723 | 3 | |
| α-helix | 724-754 | 31 | |
59 more chain groups are not listed. Open the entry in the viewer and use the sequence panel to see them.
Molecules and chains
| Molecule | Chains | Type | Length | Organism | UniProt |
|---|
| Photosystem I P700 chlorophyll a apoprotein A1 | aA, bA, cA | protein | 755 | Thermosynechococcus vestitus BP-1 | P0A405 (AlphaFold model) |
| Photosystem I P700 chlorophyll a apoprotein A2 | aB, bB, cB | protein | 741 | Thermosynechococcus vestitus BP-1 | P0A407 (AlphaFold model) |
| Photosystem I iron-sulfur center | aC, bC, cC | protein | 81 | Thermosynechococcus vestitus BP-1 | P0A415 (AlphaFold model) |
| Photosystem I reaction center subunit II | aD, bD, cD | protein | 139 | Thermosynechococcus vestitus BP-1 | P0A420 (AlphaFold model) |
| Photosystem I reaction center subunit IV | aE, bE, cE | protein | 76 | Thermosynechococcus vestitus BP-1 | P0A423 |
| Photosystem I reaction center subunit III | aF, bF, cF | protein | 164 | Thermosynechococcus vestitus BP-1 | P0A401 |
| Photosystem I reaction center subunit VIII | aI, bI, cI | protein | 38 | Thermosynechococcus vestitus BP-1 | P0A427 |
| Photosystem I reaction center subunit IX | aJ, bJ, cJ | protein | 41 | Thermosynechococcus vestitus BP-1 | P0A429 |
| Photosystem I reaction center subunit PsaK | aK, bK, cK | protein | 83 | Thermosynechococcus vestitus BP-1 | P0A425 |
| Photosystem I reaction center subunit XI | aL, bL, cL | protein | 155 | Thermosynechococcus vestitus BP-1 | Q8DGB4 |
| Photosystem I reaction center subunit XII | aM, bM, cM | protein | 31 | Thermosynechococcus vestitus BP-1 | P0A403 |
| Photosystem I 4.8K protein | aX, bX, cX | protein | 39 | Thermosynechococcus vestitus BP-1 | Q8DKP6 |
1 more molecules are not listed.
Sequence of entity 1 (aA, bA, cA), FASTA
>9LZJ_1 Photosystem I P700 chlorophyll a apoprotein A1 (chains aA, bA, cA)
MTISPPEREPKVRVVVDNDPVPTSFEKWAKPGHFDRTLARGPQTTTWIWNLHALAHDFDT
HTSDLEDISRKIFSAHFGHLAVVFIWLSGMYFHGAKFSNYEAWLADPTGIKPSAQVVWPI
VGQGILNGDVGGGFHGIQITSGLFQLWRASGITNEFQLYCTAIGGLVMAGLMLFAGWFHY
HKRAPKLEWFQNVESMLNHHLAGLLGLGSLAWAGHQIHVSLPINKLLDAGVAAKDIPLPH
EFILNPSLMAELYPKVDWGFFSGVIPFFTFNWAAYSDFLTFNGGLNPVTGGLWLSDTAHH
HLAIAVLFIIAGHMYRTNWGIGHSLKEILEAHKGPFTGAGHKGLYEVLTTSWHAQLAINL
AMMGSLSIIVAQHMYAMPPYPYLATDYPTQLSLFTHHMWIGGFLVVGGAAHGAIFMVRDY
DPAMNQNNVLDRVLRHRDAIISHLNWVCIFLGFHSFGLYVHNDTMRAFGRPQDMFSDTGI
QLQPVFAQWVQNLHTLAPGGTAPNAAATASVAFGGDVVAVGGKVAMMPIVLGTADFMVHH
IHAFTIHVTVLILLKGVLFARSSRLIPDKANLGFRFPCDGPGRGGTCQVSGWDHVFLGLF
WMYNCISVVIFHFSWKMQSDVWGTVAPDGTVSHITGGNFAQSAITINGWLRDFLWAQASQ
VIGSYGSALSAYGLLFLGAHFIWAFSLMFLFSGRGYWQELIESIVWAHNKLKVAPAIQPR
ALSIIQGRAVGVAHYLLGGIATTWAFFLARIISVG
Sequence of entity 2 (aB, bB, cB), FASTA
>9LZJ_2 Photosystem I P700 chlorophyll a apoprotein A2 (chains aB, bB, cB)
MATKFPKFSQDLAQDPTTRRIWYAIAMAHDFESHDGMTEENLYQKIFASHFGHLAIIFLW
VSGSLFHVAWQGNFEQWVQDPVNTRPIAHAIWDPQFGKAAVDAFTQAGASNPVDIAYSGV
YHWWYTIGMRTNGDLYQGAIFLLILASLALFAGWLHLQPKFRPSLSWFKNAESRLNHHLA
GLFGVSSLAWAGHLIHVAIPESRGQHVGWDNFLSTMPHPAGLAPFFTGNWGVYAQNPDTA
SHVFGTAQGAGTAILTFLGGFHPQTESLWLTDMAHHHLAIAVLFIVAGHMYRTQFGIGHS
IKEMMDAKDFFGTKVEGPFNMPHQGIYETYNNSLHFQLGWHLACLGVITSLVAQHMYSLP
PYAFIAQDHTTMAALYTHHQYIAGFLMVGAFAHGAIFLVRDYDPAQNKGNVLDRVLQHKE
AIISHLSWVSLFLGFHTLGLYVHNDVVVAFGTPEKQILIEPVFAQFIQAAHGKLLYGFDT
LLSNPDSIASTAWPNYGNVWLPGWLDAINSGTNSLFLTIGPGDFLVHHAIALGLHTTTLI
LVKGALDARGSKLMPDKKDFGYAFPCDGPGRGGTCDISAWDAFYLAMFWMLNTIGWVTFY
WHWKHLGVWEGNVAQFNESSTYLMGWLRDYLWLNSSQLINGYNPFGTNNLSVWAWMFLFG
HLVWATGFMFLISWRGYWQELIETLVWAHERTPLANLVRWKDKPVALSIVQARLVGLAHF
SVGYILTYAAFLIASTAAKFG
Sequence of entity 3 (aC, bC, cC), FASTA
>9LZJ_3 Photosystem I iron-sulfur center (chains aC, bC, cC)
MAHTVKIYDTCIGCTQCVRACPTDVLEMVPWDGCKAGQIASSPRTEDCVGCKRCETACPT
DFLSIRVYLGAETTRSMGLAY
Sequence of entity 4 (aD, bD, cD), FASTA
>9LZJ_4 Photosystem I reaction center subunit II (chains aD, bD, cD)
MTTLTGQPPLYGGSTGGLLSAADTEEKYAITWTSPKEQVFEMPTAGAAVMREGENLVYFA
RKEQCLALAAQQLRPRKINDYKIYRIFPDGETVLIHPKDGVFPEKVNKGREAVNSVPRSI
GQNPNPSQLKFTGKKPYDP
Sequence of entity 5 (aE, bE, cE), FASTA
>9LZJ_5 Photosystem I reaction center subunit IV (chains aE, bE, cE)
MVQRGSKVKILRPESYWYNEVGTVASVDQTPGVKYPVIVRFDKVNYTGYSGSASGVNTNN
FALHEVQEVAPPKKGK
Sequence of entity 6 (aF, bF, cF), FASTA
>9LZJ_6 Photosystem I reaction center subunit III (chains aF, bF, cF)
MRRFLALLLVLTLWLGFTPLASADVAGLVPCKDSPAFQKRAAAAVNTTADPASGQKRFER
YSQALCGEDGLPHLVVDGRLSRAGDFLIPSVLFLYIAGWIGWVGRAYLIAVRNSGEANEK
EIIIDVPLAIKCMLTGFAWPLAALKELASGELTAKDNEITVSPR
Sequence of entity 7 (aI, bI, cI), FASTA
>9LZJ_7 Photosystem I reaction center subunit VIII (chains aI, bI, cI)
MMGSYAASFLPWIFIPVVCWLMPTVVMGLLFLYIEGEA
Sequence of entity 8 (aJ, bJ, cJ), FASTA
>9LZJ_8 Photosystem I reaction center subunit IX (chains aJ, bJ, cJ)
MKHFLTYLSTAPVLAAIWMTITAGILIEFNRFYPDLLFHPL
Sequence of entity 9 (aK, bK, cK), FASTA
>9LZJ_9 Photosystem I reaction center subunit PsaK (chains aK, bK, cK)
MVLATLPDTTWTPSVGLVVILCNLFAIALGRYAIQSRGKGPGLPIALPALFEGFGLPELL
ATTSFGHLLAAGVVSGLQYAGAL
Sequence of entity 10 (aL, bL, cL), FASTA
>9LZJ_10 Photosystem I reaction center subunit XI (chains aL, bL, cL)
MAEELVKPYNGDPFVGHLSTPISDSGLVKTFIGNLPAYRQGLSPILRGLEVGMAHGYFLI
GPWVKLGPLRDSDVANLGGLISGIALILVATACLAAYGLVSFQKGGSSSDPLKTSEGWSQ
FTAGFFVGAMGSAFVAFFLLENFSVVDGIMTGLFN
Sequence of entity 11 (aM, bM, cM), FASTA
>9LZJ_11 Photosystem I reaction center subunit XII (chains aM, bM, cM)
MALTDTQVYVALVIALLPAVLAFRLSTELYK
Sequence of entity 12 (aX, bX, cX), FASTA
>9LZJ_12 Photosystem I 4.8K protein (chains aX, bX, cX)
MSTMATKSAKPTYAFRTFWAVLLLAINFLVAAYYFGILK
Ligands and cofactors
| ID | Name | Formula | Copies |
|---|
| CLA | Chlorophyll a | C55 H72 Mg N4 O5 | 1016 |
| PQN | Phylloquinone | C31 H46 O2 | 6 |
| SF4 | Iron/sulfur cluster | Fe4 S4 | 9 |
| BCR | Beta-carotene | C40 H56 | 238 |
| LHG | 1,2-dipalmitoyl-phosphatidyl-glycerole | C38 H75 O10 P | 18 |
| LMU | Dodecyl-alpha-D-maltoside | C24 H46 O11 | 12 |
| SQD | 1,2-di-O-acyl-3-O-[6-deoxy-6-sulfo-alpha-D-glucopyranosyl]-sn-glycerol | C41 H78 O12 S | 40 |
| LMG | 1,2-distearoyl-monogalactosyl-diglyceride | C45 H86 O10 | 12 |
| CA | Calcium ion | Ca | 3 |
Primary citation
Structural basis for the assembly and energy transfer between the cyanobacterial PSI core and the double-layered IsiA proteins. Si, L., Zhang, Y., Su, X. et al. Nat Commun (2025) 17:592-592. DOI 10.1038/s41467-025-67295-2 · PubMed
Other PDB entries of the same protein (UniProt P0A405 (AlphaFold model), which also has an AlphaFold model), best resolution first:
- 9QFP 1.74 Å, Monomeric Photosystem I Cryo-EM structure at 1.8 A resolution
- 7FIX 1.97 Å, Cryo-EM structure of cyanobacterial photosystem I in the presence of ferredoxin and…
- 1JB0 2.5 Å, Crystal Structure of Photosystem I: a Photosynthetic Reaction Center and Core Antenna…
- 7M75 2.75 Å, Room Temperature XFEL Crystallography reveals asymmetry in the vicinity of the two…
- 6TRA 2.85 Å, Cryo- EM structure of the Thermosynechococcus elongatus photosystem I in the presence of…
- 6PFY 2.9 Å, Membrane Protein Megahertz Crystallography at the European XFEL, Photosystem I at…
- 6PGK 2.9 Å, Membrane Protein Megahertz Crystallography at the European XFEL, Photosystem I XFEL at…
- 6TRC 2.98 Å, Cryo- EM structure of the Thermosynechococcus elongatus photosystem I in the presence of…
- 7M76 3.0 Å, Room Temperature XFEL Crystallography reveals asymmetry in the vicinity of the two…
- 7M78 3.0 Å, Room Temperature XFEL Crystallography reveals asymmetry in the vicinity of the two…
- 6TRD 3.16 Å, Cryo- EM structure of the Thermosynechococcus elongatus photosystem I in the presence of…
- 6LU1 3.2 Å, Cyanobacterial PSI Monomer from T. elongatus by Single Particle CRYO-EM at 3.2 A…
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