Work

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

Year: 2011

Type: article

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 dose-dependent 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 μM in the presence of putrescine. These results indicate a potential for further inhibitor development based on the dcSAH scaffold.

Source: Protein Science

DOI: 10.1002/pro.717

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

Institutions: Cornell University, Pennsylvania State University, Penn State Milton S. Hershey Medical Center, Southern Research Institute

Language: English

Topic: Polyamine Metabolism and Applications

Subfield: Molecular Biology

Field: Biochemistry, Genetics and Molecular Biology

Domain: Life Sciences

Open Access status: bronze

Funders: U.S. Department of Energy, National Institutes of Health, National Cancer Institute, National Center for Research Resources