Half way to hypusine. Molecular basis of (deoxy)hypusination

Elżbieta Wątor¹, Piotr Wilk¹, Artur Biela¹, Michał Rawski¹, Wieland Steinchen², Gert Bange², Sebastian Glatt¹,  Przemysław Grudnik¹

 ¹ Małopolska Centre of Biotechnology, Jagiellonian University, Krakow, Poland 

² Philipps-University Marburg, Center for Synthetic Microbiology (SYNMIKRO) & Faculty of Chemistry, Marburg, Germany

elzbieta.wator@doctoral.uj.edu.pl

The eukaryotic translation factor 5A (eIF5A) plays a pivotal role during translation. It is the only cellular protein known to undergo hypusination, a unique post-translational modification of a conserved lysine (Lys50 in human eIF5A). Hypusination is essential to resolve ribosomal stalling during the formation of proline-rich polypeptides. Recent findings show that the hypusination of eIF5A plays a role in many important cellular processes, including autophagy, senescence, polyamine homeostasis, and the determination of helper T cell lineages. Malfunctions of the hypusination pathway, including those caused by mutations within the pathway encoding genes, are associated with such conditions as cancer or neurodegeneration. Therefore, hypusination seems as an attractive molecular target for therapeutic interventions. 

Hypusination involves two distinct enzymatic steps. First, deoxyhypusine synthase (DHS) catalyzes the transfer of 4-aminobutyl moiety of spermidine to a specific lysine of eIF5A precursor in an NAD-dependent manner. Subsequently deoxyhypusine is further hydroxylated to the mature form hypusine by second enzyme: deoxyhypusine hydroxylase (DOHH).

Here, we present the cryoEM structure of the human eIF5A-DHS complex at 2.8Å resolution and a crystal structure of DHS trapped in the key reaction transition state. Furthermore, using combined structural biology and biochemical analysis, we show that DHS variants that cause neurodegeneration influence complex formation and hypusination efficiency. Hence, our data provide the molecular basis of deoxyhypusine synthesis and reveal how clinically-relevant mutations affect this crucial cellular process.

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2. Ganapathi M, Padgett LR, Yamada K, et al. Recessive Rare Variants in Deoxyhypusine Synthase, an Enzyme Involved in the Synthesis of Hypusine, Are Associated with a Neurodevelopmental Disorder. Am J Hum Genet. 2019;104(2):287-298.

3. Wątor E, Wilk P, Grudnik P. Half Way to Hypusine-Structural Basis for Substrate Recognition by Human Deoxyhypusine Synthase. Biomolecules. 2020;10(4):522.

The research has been supported by National Science Centre (NCN, Poland) research grant no. 2019/33/B/NZ1/01839 to P.G and 2019/35/N/NZ1/02805 to E.W.