title: Functional significance of eIF5A and its hypusine modification in eukaryotes.
abstract: The unusual basic amino acid, hypusine [N(epsilon)-(4-amino-2-hydroxybutyl)-lysine], is a modified lysine with the addition of the 4-aminobutyl moiety from the polyamine spermidine. This naturally occurring amino acid is a product of a unique posttranslational modification that occurs in only one cellular protein, eukaryotic translation initiation factor 5A (eIF5A, eIF-5A). Hypusine is synthesized exclusively in this protein by two sequential enzymatic steps involving deoxyhypusine synthase (DHS) and deoxyhypusine hydroxylase (DOHH). The deoxyhypusine/hypusine synthetic pathway has evolved in archaea and eukaryotes, and eIF5A, DHS and DOHH are highly conserved suggesting a vital cellular function of eIF5A. Gene disruption and mutation studies in yeast and higher eukaryotes have provided valuable information on the essential nature of eIF5A and the deoxyhypusine/hypusine modification in cell growth and in protein synthesis. In view of the extraordinary specificity and functional significance of hypusine-containing eIF5A in mammalian cell proliferation, eIF5A and the hypusine biosynthetic enzymes are novel potential targets for intervention in aberrant cell proliferation.
authors.affiliation: Oral and Pharyngeal Cancer Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bldg 30, Room 211, Bethesda, MD 20892-4340, USA. mhpark@nih.gov
authors.forename: M H
authors.initials: MH
authors.lastname: Park
authors.forename: K
authors.initials: K
authors.lastname: Nishimura
authors.forename: C F
authors.initials: CF
authors.lastname: Zanelli
authors.forename: S R
authors.initials: SR
authors.lastname: Valentini
mesh_terms: D000818:Animals; D001419:Bacteria / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D056890:Eukaryota / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D005658:Fungi / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008239:Lysine / Q000031:analogs & derivatives* / Q000378:metabolism; D010448:Peptide Initiation Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017433:Protein Structure, Secondary; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000097574:Eukaryotic Translation Initiation Factor 5A
chemical_list: D001426:Bacterial Proteins; D005656:Fungal Proteins; D008239:Lysine; D010448:Peptide Initiation Factors; D016601:RNA-Binding Proteins; D000097574:Eukaryotic Translation Initiation Factor 5A; C100028:hypusine