9WM8
The crystal structure of AstaP-pink1 from a microalga
Summary for 9WM8
| Entry DOI | 10.2210/pdb9wm8/pdb |
| Descriptor | AstaP-pink1, ASTAXANTHIN (3 entities in total) |
| Functional Keywords | fas1 domain superfamily, carotenoprotein, astaxanthin, coloration, bathochromic shift, lipid binding protein |
| Biological source | Scenedesmaceae sp. |
| Total number of polymer chains | 1 |
| Total formula weight | 20554.56 |
| Authors | |
| Primary citation | Mitsui, T.,Shomura, Y.,Furubayashi, M.,Kato, R.,Takaichi, S.,Kawasaki, S. Structural basis for spectral red shift and UVA absorption in the microalgal water-soluble astaxanthin-binding protein AstaP-pink1. J.Struct.Biol., 218:108288-108288, 2026 Cited by PubMed Abstract: AstaPs are water-soluble, photooxidative stress-inducible astaxanthin (AXT)-binding proteins found only in Scenedesmaceae microalgae, where they play a central role in survival under severe photooxidative stress. Here, we focused on the unique function of AstaP-pink1, which converts orange AXT into a pink form and generates a UVA absorption spectrum upon protein binding. AstaP-pink1 was expressed in genetically engineered Escherichia coli strains capable of synthesizing AXT. The host strain harboring pAC-Asta produced adonixanthin, AXT, and zeaxanthin in an approximate ratio of 5:3:2, whereas the strain carrying pMF573 predominantly produced AXT (∼90 % of total carotenoid). Co-expression of the gene encoding AstaP-pink1 in these strains resulted in moderate and selective AXT binding, accompanied by a spectral red shift and UVA absorption, thereby generating pink coloration. Crystal structure analysis of AXT-bound recombinant AstaP-pink1 (rAstaP-pink1) revealed both similarities and differences in AXT binding compared with rAstaP-orange1. Density functional theory (DFT) calculations based on the crystal structure suggested that the larger red shift than that of AstaP-orange1 and the distinct UVA absorption are derived from the conformation of AXT that is compelled by binding to AstaP-pink1. This study suggests that AXT binding by AstaP-pink1 not only facilitates the water solubilization of AXT but also generates the observed spectral properties. PubMed: 41500483DOI: 10.1016/j.jsb.2026.108288 PDB entries with the same primary citation |
| Experimental method | X-RAY DIFFRACTION (1.7 Å) |
Structure validation
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