Institute for Quantum Life Science, National Institutes for Quantum Science and Technology, Tokai, Ibaraki, Japan.
Graduate School of Science and Technology, Gunma University, Maebashi, Gunma, Japan.
Protein Sci. 2022 Jun;31(6):e4313. doi: 10.1002/pro.4313.
Pigeon iron-sulfur (Fe-S) cluster assembly 1 homolog (clISCA1) is a target protein for research into the biomagnetoreception mechanism, as the clCRY4/clISCA1 oligomer, a complex composed of the columnar clISCA1 oligomer and the magnetosensor candidate protein cryptochrome-4 (clCRY4) oligomer, tends to orient itself along weak magnetic fields, such as geomagnetic fields, under blue light. To obtain insight into the magnetic orientation mechanism of the clCRY4/clISCA1 oligomer, we inspected magnetic field effects on the structure and molecular behavior of clISCA1 by small angle X-ray scattering analysis. The results indicated that the clISCA1 protomer took the Fe-S cluster-bound globular form and unbound rod-like form. The globular clISCA1 protomer assembled to form columnar oligomers, which allowed for the binding of many Fe-S clusters at the interface between clISCA1 protomers. Moreover, the translational diffusion and the columnar oligomerization of clISCA1 were controlled by the external static magnetic field and Fe-S clusters bound to clISCA1. However, the columnar clISCA1 oligomer was not oriented along the external static magnetic field (~1 T) when clCRY4 was not bound to clISCA1. This result indicated that clCRY4 has a function to enhance the magnetic orientational property of clCRY4/clISCA1 oligomer.
鸽子铁硫（Fe-S）簇组装 1 同源物（clISCA1）是生物磁感受机制研究的目标蛋白，因为由柱状 clISCA1 寡聚物和磁传感器候选蛋白隐花色素-4（clCRY4）寡聚物组成的 clCRY4/clISCA1 寡聚物复合物，在蓝光下往往会沿着弱磁场（如地磁场）定向。为了深入了解 clCRY4/clISCA1 寡聚物的磁定向机制，我们通过小角度 X 射线散射分析检查了磁场对 clISCA1 结构和分子行为的影响。结果表明，clISCA1 原聚体呈 Fe-S 簇结合的球形和未结合的棒状。球形 clISCA1 原聚体组装成柱状寡聚物，允许在 clISCA1 原聚体之间的界面处结合许多 Fe-S 簇。此外，clISCA1 的平动扩散和柱状寡聚化受外部静磁场和与 clISCA1 结合的 Fe-S 簇的控制。然而，当 clCRY4 未与 clISCA1 结合时，柱状 clISCA1 寡聚物不会沿外部静磁场（约 1 T）定向。这一结果表明，clCRY4 具有增强 clCRY4/clISCA1 寡聚物磁定向性质的功能。
