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PDBsum entry 2fft
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Plant protein
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PDB id
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2fft
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References listed in PDB file
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Key reference
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Title
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Micelle-Induced folding of spinach thylakoid soluble phosphoprotein of 9 kda and its functional implications.
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Authors
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J.Song,
M.S.Lee,
I.Carlberg,
A.V.Vener,
J.L.Markley.
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Ref.
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Biochemistry, 2006,
45,
15633-15643.
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PubMed id
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Abstract
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Thylakoid soluble phosphoprotein of 9 kDa (TSP9) has been identified as a
plant-specific protein in the photosynthetic thylakoid membrane (Carlberg et al.
(2003) Proc. Natl. Acad. Sci. 100, 757-762). Nonphosphorylated TSP9 is
associated with the membrane, whereas, after light-induced phosphorylation, a
fraction of the phosphorylated TSP9 is released into the aqueous stroma. By NMR
spectroscopy, we have determined the structural features of nonphosphorylated
TSP9 both in aqueous solution and in membrane mimetic micelles. The results show
that both wild type nonphosphorylated TSP9 and a triple-mutant (T46E + T53E +
T60E) mimic of the triphosphorylated form of TSP9 are disordered under aqueous
conditions, but adopt an ordered conformation in the presence of detergent
micelles. The micelle-induced structural features, which are similar in micelles
either of SDS or dodecylphosphocholine (DPC), consist of an N-terminal
alpha-helix, which may represent the primary site of interaction between TSP9
and binding partners, and a less structured helical turn near the C-terminus.
These structured elements contain mainly hydrophobic residues. NMR relaxation
data for nonphosphorylated TSP9 in SDS micelles indicated that the molecule is
highly flexible with the highest order in the N-terminal alpha-helix.
Intermolecular NOE signals, as well as spin probe-induced broadening of NMR
signals, demonstrated that the SDS micelles contact both the structured and a
portion of the unstructured regions of TSP9, in particular, those containing the
three phosphorylation sites (T46, T53, and T60). This interaction may explain
the selective dissociation of phosphorylated TSP9 from the membrane. Our study
presents a structural model for the role played by the structured and
unstructured regions of TSP9 in its membrane association and biological function.
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