Site-Directed Spin-Labeling Study of the Light-Harvesting Complex CP29

AUTOR(ES)

Kavalenka, Aleh A.

FONTE

The Biophysical Society

RESUMO

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.

Documentos Relacionados

• Interactions of the GM2 Activator Protein with Phosphatidylcholine Bilayers: A Site-Directed Spin-Labeling Power Saturation Study
• Specific spin-labeling of transfer ribonucleic acid molecules.
• A transmembrane form of annexin XII detected by site-directed spin labeling
• Structure of membrane-bound α-synuclein studied by site-directed spin labeling
• Environmental effects on the light-harvesting complex of cyanobacteria.