Modulation of MagR magnetic properties via iron–sulfur cluster binding

Iron–sulfur clusters are essential cofactors found in all kingdoms of life and play essential roles in fundamental processes, including but not limited to respiration, photosynthesis, and nitrogen fixation. The chemistry of iron–sulfur clusters makes them ideal for sensing various redox environmental signals, while the physics of iron–sulfur clusters and its host proteins have been long overlooked. One such protein, MagR, has been proposed as a putative animal magnetoreceptor. It forms a rod-like complex with cryptochromes (Cry) and possesses intrinsic magnetic moment. However, the magnetism modulation of MagR remains unknown. Here in this study, iron–sulfur cluster binding in MagR has been characterized. Three conserved cysteines of MagR play different roles in iron–sulfur cluster binding. Two forms of iron–sulfur clusters binding have been identified in pigeon MagR and showed different magnetic properties: [3Fe–4S]-MagR appears to be superparamagnetic and has saturation magnetization at 5 K but [2Fe–2S]-MagR is paramagnetic. While at 300 K, [2Fe–2S]-MagR is diamagnetic but [3Fe–4S]-MagR is paramagnetic. Together, the different types of iron–sulfur cluster binding in MagR attribute distinguished magnetic properties, which may provide a fascinating mechanism for animals to modulate the sensitivity in magnetic sensing.

The Iron Maiden. Cytosolic Aconitase/IRP1 Conformational Transition in the Regulation of Ferritin Translation and Iron Hemostasis

Maintaining iron homeostasis is fundamental for almost all living beings, and its deregulation correlates with severe and debilitating pathologies. The process is made more complicated by the omnipresence of iron and by its role as a fundamental component of a number of crucial metallo proteins. The response to modifications in the amount of the free-iron pool is performed via the inhibition of ferritin translation by sequestering consensus messenger RNA (mRNA) sequences. In turn, this is regulated by the iron-sensitive conformational equilibrium between cytosolic aconitase and IRP1, mediated by the presence of an iron–sulfur cluster. In this contribution, we analyze by full-atom molecular dynamics simulation, the factors leading to both the interaction with mRNA and the conformational transition. Furthermore, the role of the iron–sulfur cluster in driving the conformational transition is assessed by obtaining the related free energy profile via enhanced sampling molecular dynamics simulations.

The iron maiden. Cytosolic aconitase/IRP1 conformational transition in the regulation of ferritin translation and iron hemostasis

Maintaining iron homeostasis is fundamental for almost all living being, and its deregulation correlates with severe and debilitating pathologies. The process is made more complicated by the omnipresence of iron and by its role as a fundamental component of a number of crucial metallo proteins. The response to modifications in the amount of the free iron pool is performed via the inhibition of ferritin translation by sequestering consensus messenger RNA (mRNA) sequences. In turn this is regulated by the iron-sensitive conformational equilibrium between aconitase and IRP, mediated by the presence of an iron-sulfur cluster. In this contribution we analyze by full-atom molecular dynamics simulation, the factors leading to both the interaction with mRNA, and the conformational transition. Furthermore, the role of the iron-sulfur cluster in driving the confor-mational transition is assessed by obtaining the related free energy profile via enhanced sampling molecular dynamics simulations.