Site-directed spin labeling study of the light-harvesting complex CP29

A.A. Kavalenka, R.B. Spruijt, C.J.A.M. Wolfs, J. Strancar, R. Croce, M.A. Hemminga, H. van Amerongen

Research output: Contribution to journalArticleAcademicpeer-review

5 Citations (Scopus)

Abstract

The topology of the long N-terminal domain (100 amino-acid residues) of the photosynthetic Lhc CP29 was studied using electron spin resonance. Wild-type protein containing a single cysteine at position 108 and nine single-cysteine mutants were produced, allowing to label different parts of the domain with a nitroxide spin label. In all cases, the apoproteins were either solubilized in detergent or they were reconstituted with their native pigments (holoproteins) in vitro. The spin-label electron spin resonance spectra were analyzed in terms of a multicomponent spectral simulation approach, based on hybrid evolutionary optimization and solution condensation. These results permit to trace the structural organization of the long N-terminal domain of CP29. Amino-acid residues 97 and 108 are located in the transmembrane pigment-containing protein body of the protein. Positions 65, 81, and 90 are located in a flexible loop that is proposed to extend out of the protein from the stromal surface. This loop also contains a phosphorylation site at Thr81, suggesting that the flexibility of this loop might play a role in the regulatory mechanisms of the light-harvesting process. Positions 4, 33, 40, and 56 are found to be located in a relatively rigid environment, close to the transmembrane protein body. On the other hand, position 15 is located in a flexible region, relatively far away from the transmembrane domain
Original languageEnglish
Pages (from-to)3620-3628
JournalBiophysical Journal
Volume96
Issue number9
DOIs
Publication statusPublished - 2009

Keywords

  • chlorophyll-a/b protein
  • photosystem-ii subunit
  • plant antenna protein
  • n-terminal domain
  • energy-transfer
  • conformational-changes
  • biosystem complexity
  • membrane-proteins
  • escherichia-coli
  • binding protein

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