Binding and inhibition of human spermidine synthase by decarboxylated S-adenosylhomocysteine

Jolita Šečkute, Diane E. McCloskey, H. Jeanette Thomas, John A. Secrist, Anthony E. Pegg, Steven E. Ealick

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

Aminopropyltransferases are essential enzymes that form polyamines in eukaryotic and most prokaryotic cells. Spermidine synthase (SpdS) is one of the most well-studied enzymes in this biosynthetic pathway. The enzyme uses decarboxylated S-adenosylmethionine and a short-chain polyamine (putrescine) to make a medium-chain polyamine (spermidine) and 5′-deoxy-5′- methylthioadenosine as a byproduct. Here, we report a new spermidine synthase inhibitor, decarboxylated S-adenosylhomocysteine (dcSAH). The inhibitor was synthesized, and dosedependent inhibition of human, Thermatoga maritima, and Plasmodium falciparum spermidine synthases, as well as functionally homologous human spermine synthase, was determined. The human SpdS/dcSAH complex structure was determined by X-ray crystallography at 2.0 Å resolution and showed consistent active site positioning and coordination with previously known structures. Isothermal calorimetry binding assays confirmed inhibitor binding to human SpdS with K d of 1.1 ± 0.3 μM in the absence of putrescine and 3.2 ± 0.1 lM in the presence of putrescine. These results indicate a potential for further inhibitor development based on the dcSAH scaffold. Published by Wiley-Blackwell.

Original languageEnglish (US)
Pages (from-to)1836-1844
Number of pages9
JournalProtein Science
Volume20
Issue number11
DOIs
StatePublished - Nov 2011

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology

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