Mitochondrial targeting sequence of magnetoreceptor MagR:More than just targeting

Iron-sulfur clusters(ISC)are essential cofactors for proteins involved in various biological processes,such as electron transport,biosynthetic reactions,DNA repair,and gene expression regulation.ISC assembly protein IscA1(or MagR)is found within the mitochondria of most eukaryotes.Magnetoreceptor(MagR)is a highly conserved A-type iron and iron-sulfur cluster-binding protein,characterized by two distinct types of iron-sulfur clusters,[2Fe-2S]and[3Fe-4S],each conferring unique magnetic properties.MagR forms a rod-like polymer structure in complex with photoreceptive cryptochrome(Cry)and serves as a putative magnetoreceptor for retrieving geomagnetic information in animal navigation.Although the N-terminal sequences of MagR vary among species,their specific function remains unknown.In the present study,we found that the N-terminal sequences of pigeon MagR,previously thought to serve as a mitochondrial targeting signal(MTS),were not cleaved following mitochondrial entry but instead modulated the efficiency with which iron-sulfur clusters and irons are bound.Moreover,the N-terminal region of MagR was required for the formation of a stable MagR/Cry complex.Thus,the N-terminal sequences in pigeon MagR fulfil more important functional roles than just mitochondrial targeting.These results further extend our understanding of the function of MagR and provide new insights into the origin of magnetoreception from an evolutionary perspective.

Magnetic Fields Affect Alcoholic Liver Disease by Liver Cell Oxidative Stress and Proliferation Regulation

It is well known that alcohol consumption leads to substantially increased free radical levels and health risks,which lacks effective treatment besides alcohol abstinence.Here,we compared different static magnetic field(SMF)settings and found that a downward quasi-uniform SMF of~0.1 to 0.2 T could effectively alleviate alcohol-induced liver damage and lipid accumulation and improve hepatic function.SMFs of two different directions can reduce the inflammation,reactive oxygen species levels,and oxidative stress in the liver,while the downward SMF had more obvious effects.Moreover,we found that the upward direction SMF of~0.1 to 0.2 T could inhibit DNA synthesis and regeneration in hepatocytes,which caused detrimental effects on the lifespan of"heavy drinking"mice.In contrast,the downward SMF prolongs survival of"heavy drinking"mice.On one hand,our study shows that~0.1 to 0.2 T moderate quasi-uniform SMFs with a downward direction have great promises to be developed into a physical method to reduce alcohol-induced liver damage;on the other hand,although the internationally recognized upper limit for SMF public exposure is 0.4 T,people should also pay extra attention to SMF strength,direction,and inhomogeneity that could generate harmful effects on specific severe pathological conditions.