1zgq
Crystal Structure of the Discosoma Red Fluorescent Protein (DsRed) Variant Q66M
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OverviewOverview
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.
About this StructureAbout this Structure
1ZGQ is a Single protein structure of sequence from Discosoma sp. with PEG as ligand. Full crystallographic information is available from OCA.
ReferenceReference
Crystallographic structures of Discosoma red fluorescent protein with immature and mature chromophores: linking peptide bond trans-cis isomerization and acylimine formation in chromophore maturation., Tubbs JL, Tainer JA, Getzoff ED, Biochemistry. 2005 Jul 26;44(29):9833-40. PMID:16026155
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