Pletneva Nadezhda, Pletnev Sergei, Tikhonova Tamara, Popov Vladimir, Martynov Vladimir, Pletnev Vladimir
Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Science, Moscow, Russia.
Acta Crystallogr D Biol Crystallogr. 2006 May;62(Pt 5):527-32. doi: 10.1107/S0907444906007852. Epub 2006 Apr 19.
The three-dimensional structure of the red fluorescent protein (RFP) zRFP574 from the button polyp Zoanthus sp. (two dimers per asymmetric unit, 231 x 4 amino acids) has been determined at 2.4 A resolution in space group C222(1). The crystal structure, refined to a crystallographic R factor of 0.203 (R(free) = 0.249), adopts the beta-barrel fold composed of 11 strands similar to that of the yellow fluorescent protein zYFP538. The zRFP574 chromophore, originating from the protein sequence Asp66-Tyr67-Gly68, has a two-ring structure typical of GFP-like proteins. The bond geometry of residue 66 shows the strong tendency of the corresponding C(alpha) atom to sp(2) hybridization as a consequence of N-acylimine bond formation. The zRFP574 chromophore contains the 65-66 cis-peptide bond characteristic of red fluorescent proteins. The chromophore phenolic ring adopts a cis conformation coplanar with the imidazolinone ring. The crystallographic study has revealed an unexpected chemical feature of the internal chromophore. A decarboxylated side chain of the chromophore-forming residue Asp66 has been observed in the structure. This additional post-translational modification is likely to play a key role in the bathochromic shift of the zRFP574 spectrum.
纽扣海葵（Zoanthus sp.）红色荧光蛋白（RFP）zRFP574（每个不对称单元有两个二聚体，231×4个氨基酸）的三维结构已在空间群C222(1)中以2.4埃分辨率确定。晶体结构经精修后，晶体学R因子为0.203（R(free)=0.249），其采用由11条链组成的β桶折叠结构，与黄色荧光蛋白zYFP538的结构相似。zRFP574生色团源自蛋白质序列Asp66-Tyr67-Gly68，具有典型的类绿色荧光蛋白的双环结构。残基66的键几何结构显示，由于形成了N-酰亚胺键，相应的C(α)原子有强烈的sp(2)杂化倾向。zRFP574生色团含有红色荧光蛋白特有的65-66顺式肽键。生色团酚环与咪唑啉酮环共面呈顺式构象。晶体学研究揭示了内部生色团一个意想不到的化学特征。在结构中观察到了生色团形成残基Asp66的脱羧侧链。这种额外的翻译后修饰可能在zRFP574光谱的红移中起关键作用。
