Journal Article

PHPPUBDB-25674

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Structural comparison of the poplar plastocyanin isoforms PCa and PCb sheds new light on the role of the copper site geometry in interactions with redox partners in oxygenic photosynthesis

Kachalova, G. S. ; Shosheva, A. C. ; Bourenkov, G. P. ; Donchev, A. A. ; Dimitrov, M. I. ; Bartunik, H. D. ; DESY

2012
Elsevier New York, NY [u.a.]

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Please use a persistent id in citations: doi:10.1016/j.jinorgbio.2012.07.015

Abstract: Plastocyanin (PC) from poplar leaves is present in two isoforms, PCa and PCb, which differ in sequence by amino acid replacements at locations remote from the copper center and simultaneously act in the photosynthetic electron-transport chain. We describe ultra-high resolution structures of PCa and high-resolution structures of PCb, both under oxidizing and reducing conditions at pH 4, 6 and 8. The docking on cytochrome f and photosystem I, respectively, has been modeled for both isoforms. PCa and PCb exhibit closely similar overall and active-site structures, except for a difference in the relative orientation of the acidic patches. The isoforms exhibit substantial differences in the dependence of the reduced (Cu(I)) geometry on pH. In PCa, the decrease in pH causes a gradual dissociation of His87 from Cu(I) at low pH, probably adopting a neutral tautomeric state. In PCb, the histidine remains covalently bound to Cu(I) and may adopt a doubly protonated state at low pH. The fact that both isoforms have similar although not identical functions in photosynthetic electron flows suggests that the His87 imidazole does not play a crucial role for the pathway of electron transport from cytochrome f to oxidized PC.

Keyword(s): Copper: chemistry (MeSH) ; Copper: metabolism (MeSH) ; Cytochromes f: chemistry (MeSH) ; Cytochromes f: metabolism (MeSH) ; Hydrogen-Ion Concentration (MeSH) ; Oxidation-Reduction (MeSH) ; Photosynthesis: physiology (MeSH) ; Photosystem I Protein Complex: chemistry (MeSH) ; Photosystem I Protein Complex: metabolism (MeSH) ; Plastocyanin: chemistry (MeSH) ; Plastocyanin: metabolism (MeSH) ; Populus: chemistry (MeSH) ; Populus: metabolism (MeSH) ; Protein Isoforms: chemistry (MeSH) ; Protein Isoforms: metabolism (MeSH) ; Photosystem I Protein Complex ; Protein Isoforms ; Copper ; Plastocyanin ; Cytochromes f

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Contributing Institute(s):

1. Experiments with synchrotron radiation (HASYLAB)

Research Program(s):

1. DORIS Beamline BW6 (POF2-54G13) (POF2-54G13)

Experiment(s):

1. DORIS Beamline BW6 (DORIS III)

Appears in the scientific report 2012

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Database coverage:
; BIOSIS Previews ; Current Contents - Life Sciences ; Current Contents - Physical, Chemical and Earth Sciences ; JCR ; NCBI Molecular Biology Database ; Nationallizenz ; No Author Disambiguation ; SCOPUS ; Science Citation Index ; Science Citation Index Expanded ; Thomson Reuters Master Journal List ; Web of Science Core Collection

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