A trypanosomatid protein specifically interacts with a mammalian iron-responsive element.
Intracellular iron homeostasis of vertebrates and invertebrates is mediated through the interaction of iron-regulatory proteins (IRPs) with mRNAs containing a bulged hairpin-loop structure termed the iron-responsive element (IRE). We detected a protein within extracts prepared from Leishmania tarentolae that specifically interacts with a mammalian IRE; mutations to the IRE that inhibit the interaction with the mammalian protein have a corresponding effect on the interaction with the L. tarentolae protein. The disassociation constant noted for the interaction of the mammalian IRE with the L. tarentolae protein was 0.7+/-0.3 microM, whereas that recorded for the interaction with the mammalian IRP under these conditions was 5+/-2 nM. The interacting L. tarentolae protein potentially places the RNA-binding site of the IRP near the root of the eukaryotic evolutionary tree. However, unlike that of the mammalian IRPs, the L. tarentolae IRE-binding activity was not induced by growth in iron-depleted media.
Meehan
H A
HA
Department of Pharmacology, University of Minnesota, Minneapolis 55455-0347, USA.
Lundberg
R A
RA
Connell
G J
GJ
D000818:Animals; D007501:Iron / Q000378:metabolism*; D035925:Iron-Regulatory Proteins; D007506:Iron-Sulfur Proteins / Q000378:metabolism*; D007891:Leishmania / Q000378:metabolism*; D011485:Protein Binding; D015800:Protozoan Proteins / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000378:metabolism*; D020218:Response Elements
D035925:Iron-Regulatory Proteins; D007506:Iron-Sulfur Proteins; D015800:Protozoan Proteins; D016601:RNA-Binding Proteins; D007501:Iron