module: dmel_hypusine_biosynthesis
title: Hypusine biosynthesis in Drosophila melanogaster
label: Hypusine biosynthesis
module_type: METABOLIC_PATHWAY
description: >-
  Hypusine is a modified lysine found only in translation factor eIF5A, where it
  is needed for eIF5A to support translation elongation through difficult
  sequences such as polyproline stretches. It is made in two steps.
  Deoxyhypusine synthase (Dhps) transfers the aminobutyl group of spermidine to
  a specific lysine of eIF5A, forming deoxyhypusine. Deoxyhypusine hydroxylase,
  encoded in Drosophila by nero, then hydroxylates this residue to hypusine.
  In flies, nero mutations affect cell and organ growth and autophagy.
summary: >-
  Dhps and Nero modify a lysine of eIF5A to hypusine using spermidine.
concepts:
  - {id: GO:0008612, label: peptidyl-hypusine biosynthetic process}
parts:
  - id: deoxyhypusine_synthesis
    label: Deoxyhypusine synthesis
    role: spermidine-dependent eIF5A lysine aminobutylation
    genes: [Dhps]
    function: {id: GO:0034038, label: deoxyhypusine synthase activity}
  - id: deoxyhypusine_hydroxylation
    label: Deoxyhypusine hydroxylation
    role: deoxyhypusine to hypusine
    genes: [nero]
    function: {id: GO:0019135, label: deoxyhypusine monooxygenase activity}
connections:
  - source: deoxyhypusine_synthesis
    target: deoxyhypusine_hydroxylation
    connection_type: PRECEDES
    description: Deoxyhypusyl-eIF5A made by Dhps is hydroxylated by Nero.
notes: >-
  Boundary. eIF5A is the substrate of both enzymes and is not modelled as a
  part; spermidine synthesis is upstream context.
group: HYPUBIO