2ojk
From Proteopedia
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Crystal Structure of Green Fluorescent Protein from Zoanthus sp at 2.2 A Resolution
Overview
The three-dimensional structures of the wild-type red (zRFP574) and green, (zGFP506) fluorescent proteins (FP) from the button polyp Zoanthus have, been determined at 1.51 and 2.2 A resolution, respectively. In addition, the crystal structures of a zGFP506 variant (zGFP506_N66D) with, replacement of the first chromophore-forming residue (Asn66 to Asp) have, been determined in the transitional ;green' and mature ;red' states at 2.4, and 2.2 A, respectively. The monomers of these proteins adopt the typical, fold of the green fluorescent protein (GFP) family, consisting of an, 11-stranded beta-barrel with a chromophore embedded in the middle of an, internal alpha-helix directed along the beta-barrel axis., Post-translational modification of the chromophore-forming sequence, Asn66-Tyr67-Gly68 within zGFP506 results in a typical GFP-like coplanar, two-ring structure consisting of a five-membered imidazolinone heterocycle, with the phenolic ring of Tyr67 in a cis orientation to the C(alpha)-N(67), bond. A novel post-translational modification of the chromophore-forming, sequence Asp66-Tyr67-Gly68 in zRFP574 expands the protein maturation, beyond the green-emitting form and results in decarboxylation of the Asp66, side chain. It is suggested that electrostatic conflict between the, closely spaced negatively charged side chains of the chromophore Asp66 and, the proximal catalytic Glu221 is most likely to be the trigger for the, chain of reactions resulting in the observed decarboxylation. The, chromophore structures of wild-type zGFP506 and of its mutant zGFP506_N66D, in the ;green' and ;red' states support this suggestion. The beta-barrel, frames of zRFP574 and zGFP506 reveal the presence of a water-filled pore, leading to the chromophore Tyr67, similar to that observed previously in, TurboGFP. An analysis of the residue composition at two inter-monomer, interfaces in the tetrameric biological unit of zRFP574 and zGFP506, as, well as of zYFP538 from the same species, has revealed a group of highly, conserved residues that are apparently responsible for oligomerization., These residues present initial useful targets for rational mutagenesis, aimed at designing monomeric forms of the fluorescent proteins, which are, more suitable for practical applications.
About this Structure
2OJK is a Single protein structure of sequence from Zoanthus sp.. Full crystallographic information is available from OCA.
Reference
Refined crystal structures of red and green fluorescent proteins from the button polyp Zoanthus., Pletneva N, Pletnev V, Tikhonova T, Pakhomov AA, Popov V, Martynov VI, Wlodawer A, Dauter Z, Pletnev S, Acta Crystallogr D Biol Crystallogr. 2007 Oct;63(Pt 10):1082-93. Epub 2007, Sep 19. PMID:17881826
Page seeded by OCA on Wed Jan 23 13:06:44 2008
