title: Involvement of the iron regulatory protein from Eisenia andrei earthworms in the regulation of cellular iron homeostasis.
abstract: Iron homeostasis in cells is regulated by iron regulatory proteins (IRPs) that exist in different organisms. IRPs are cytosolic proteins that bind to iron-responsive elements (IREs) of the 5'- or 3'-untranslated regions (UTR) of mRNAs that encode many proteins involved in iron metabolism. In this study, we have cloned and described a new regulatory protein belonging to the family of IRPs from the earthworm Eisenia andrei (EaIRP). The earthworm IRE site in 5'-UTR of ferritin mRNA most likely folds into a secondary structure that differs from the conventional IRE structures of ferritin due to the absence of a typically unpaired cytosine that participates in protein binding. Prepared recombinant EaIRP and proteins from mammalian liver extracts are able to bind both mammalian and Eisenia IRE structures of ferritin mRNA, although the affinity of the rEaIRP/Eisenia IRE structure is rather low. This result suggests the possible contribution of a conventional IRE structure. When IRP is supplemented with a Fe-S cluster, it can function as a cytosolic aconitase. Cellular cytosolic and mitochondrial fractions, as well as recombinant EaIRP, exhibit aconitase activity that can be abolished by the action of oxygen radicals. The highest expression of EaIRP was detected in parts of the digestive tract. We can assume that earthworms may possess an IRE/IRP regulatory network as a potential mechanism for maintaining cellular iron homeostasis, although the aconitase function of EaIRP is most likely more relevant.
authors.affiliation: Laboratory of Cellular and Molecular Immunology, Institute of Microbiology of the Academy of Sciences of the Czech Republic, v. v. i., Prague 4, Czech Republic.
authors.forename: Petra
authors.initials: P
authors.lastname: Procházková
authors.affiliation: Laboratory of Cellular and Molecular Immunology, Institute of Microbiology of the Academy of Sciences of the Czech Republic, v. v. i., Prague 4, Czech Republic.
authors.forename: František
authors.initials: F
authors.lastname: Škanta
authors.affiliation: Laboratory of Cellular and Molecular Immunology, Institute of Microbiology of the Academy of Sciences of the Czech Republic, v. v. i., Prague 4, Czech Republic.
authors.forename: Radka
authors.initials: R
authors.lastname: Roubalová
authors.affiliation: Laboratory of Cellular and Molecular Immunology, Institute of Microbiology of the Academy of Sciences of the Czech Republic, v. v. i., Prague 4, Czech Republic.
authors.forename: Marcela
authors.initials: M
authors.lastname: Šilerová
authors.affiliation: Laboratory of Cellular and Molecular Immunology, Institute of Microbiology of the Academy of Sciences of the Czech Republic, v. v. i., Prague 4, Czech Republic.
authors.forename: Jiří
authors.initials: J
authors.lastname: Dvořák
authors.affiliation: Laboratory of Cellular and Molecular Immunology, Institute of Microbiology of the Academy of Sciences of the Czech Republic, v. v. i., Prague 4, Czech Republic.
authors.forename: Martin
authors.initials: M
authors.lastname: Bilej
mesh_terms: D000154:Aconitate Hydratase / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D005293:Ferritins / Q000378:metabolism*; D006706:Homeostasis / Q000502:physiology*; D007501:Iron / Q000378:metabolism*; D035925:Iron-Regulatory Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D009835:Oligochaeta / Q000254:growth & development / Q000378:metabolism*; D010802:Phylogeny; D011485:Protein Binding; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid
chemical_list: D035925:Iron-Regulatory Proteins; D012333:RNA, Messenger; D005293:Ferritins; D007501:Iron; D000154:Aconitate Hydratase