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Title
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Photosystem I at 4 A resolution represents the first structural model of a joint photosynthetic reaction centre and core antenna system.
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Authors
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N.Krauss,
W.D.Schubert,
O.Klukas,
P.Fromme,
H.T.Witt,
W.Saenger.
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Ref.
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Nat Struct Biol, 1996,
3,
965-973.
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PubMed id
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Abstract
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The 4 A X-ray structure model of trimeric photosystem I of the cyanobacterium
Synechococcus elongatus reveals 31 transmembrane, nine surface and three stromal
alpha-helices per monomer, assigned to the 11 protein subunits: PsaA and PsaB
are related by a pseudo two-fold axis normal to the membrane plane, along which
the electron transfer pigments are arranged. 65 antenna chlorophyll a (Chl a)
molecules separated by < or = 16 A form an oval, clustered net continuous
with the electron transfer chain through the second and third Chl a pairs of the
electron transfer system. This suggests a dual role for these Chl a both in
excitation energy and electron transfer. The architecture of the protein core
indicates quinone and iron-sulphur type reaction centres to have a common
ancestor.
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