Functional significance of eIF5A and its hypusine modification in eukaryotes
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Park, M. H.
Zanelli, Cleslei Fernando [UNESP]
Valentini, Sandro Roberto [UNESP]
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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.
Hypusine, eIF5A, Posttranslational modification, Polyamine, Deoxyhypusine synthase, Deoxyhypusine hydroxylase, Gene inactivation
Amino Acids. New York: Springer, v. 38, n. 2, p. 491-500, 2010.