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PDBsum entry 1zgo
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Luminescent protein
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PDB id
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1zgo
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References listed in PDB file
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Key reference
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Title
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Crystallographic structures of discosoma red fluorescent protein with immature and mature chromophores: linking peptide bond trans-Cis isomerization and acylimine formation in chromophore maturation.
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Authors
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J.L.Tubbs,
J.A.Tainer,
E.D.Getzoff.
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Ref.
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Biochemistry, 2005,
44,
9833-9840.
[DOI no: ]
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PubMed id
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Abstract
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The mature self-synthesizing p-hydroxybenzylideneimidazolinone-like fluorophores
of Discosoma red fluorescent protein (DsRed) and Aequorea victoria green
fluorescent protein (GFP) are extensively studied as powerful biological
markers. Yet, the spontaneous formation of these fluorophores by cyclization,
oxidation, and dehydration reactions of tripeptides within their protein
environment remains incompletely understood. The mature DsRed fluorophore (Gln
66, Tyr 67, and Gly 68) differs from the GFP fluorophore by an acylimine that
results in Gln 66 Calpha planar geometry and by a Phe 65-Gln 66 cis peptide
bond. DsRed green-to-red maturation includes a green-fluorescing immature
chromophore and requires a chromophore peptide bond trans-cis isomerization that
is slow and incomplete. To clarify the unique structural chemistry for the
individual immature "green" and mature "red" chromophores of DsRed, we report
here the determination and analysis of crystal structures for the wild-type
protein (1.4 A resolution), the entirely green DsRed K70M mutant protein (1.9 A
resolution), and the DsRed designed mutant Q66M (1.9 A resolution), which shows
increased red chromophore relative to the wild-type DsRed. Whereas the mature,
red-fluorescing chromophore has the expected cis peptide bond and a
sp(2)-hybridized Gln 66 Calpha with planar geometry, the crystal structure of
the immature green-fluorescing chromophore of DsRed, presented here for the
first time, reveals a trans peptide bond and a sp(3)-hybridized Gln 66 Calpha
with tetrahedral geometry. These results characterize a GFP-like immature green
DsRed chromophore structure, reveal distinct mature and immature chromophore
environments, and furthermore provide evidence for the coupling of acylimine
formation with trans-cis isomerization.
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