6LJC
Crystal structure of fragmin F2-F3 domains (calcium and magnesium condition)
Summary for 6LJC
| Entry DOI | 10.2210/pdb6ljc/pdb |
| Descriptor | Actin-binding protein fragmin P, CALCIUM ION, 2-(N-MORPHOLINO)-ETHANESULFONIC ACID, ... (8 entities in total) |
| Functional Keywords | fragmin, gelsolin family protein, calcium regulation, actin filament severing, cytosolic protein |
| Biological source | Physarum polycephalum (Slime mold) |
| Total number of polymer chains | 1 |
| Total formula weight | 23715.58 |
| Authors | Takeda, S. (deposition date: 2019-12-14, release date: 2020-01-01, Last modification date: 2023-11-22) |
| Primary citation | Takeda, S.,Fujiwara, I.,Sugimoto, Y.,Oda, T.,Narita, A.,Maeda, Y. Novel inter-domain Ca2+-binding site in the gelsolin superfamily protein fragmin. J.Muscle Res.Cell.Motil., 41:153-162, 2020 Cited by PubMed Abstract: Gelsolin superfamily proteins, consisting of multiple domains (usually six), sever actin filaments and cap the barbed ends in a Ca-dependent manner. Two types of evolutionally conserved Ca-binding sites have been identified in this family; type-1 (between gelsolin and actin) and type-2 (within the gelsolin domain). Fragmin, a member in the slime mold Physarum polycephalum, consists of three domains (F1-F3) that are highly similar to the N-terminal half of mammalian gelsolin (G1-G3). Despite their similarities, the two proteins exhibit a significant difference in the Ca dependency; F1-F3 absolutely requires Ca for the filament severing whereas G1-G3 does not. In this study, we examined the strong dependency of fragmin on Ca using biochemical and structural approaches. Our co-sedimentation assay demonstrated that Ca significantly enhanced the binding of F2-F3 to actin. We determined the crystal structure of F2-F3 in the presence of Ca. F2-F3 binds a total of three calcium ions; while two are located in type-2 sites within F2 or F3, the remaining one resides between the F2 long helix and the F3 short helix. The inter-domain Ca-coordination appears to stabilize F2-F3 in a closely packed configuration. Notably, the F3 long helix exhibits a bent conformation which is different from the straight G3 long helix in the presence of Ca. Our results provide the first structural evidence for the existence of an unconventional Ca-binding site in the gelsolin superfamily proteins. PubMed: 31863323DOI: 10.1007/s10974-019-09571-5 PDB entries with the same primary citation |
| Experimental method | X-RAY DIFFRACTION (1.85 Å) |
Structure validation
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