2JEV

Crystal structure of human spermine,spermidine acetyltransferase in complex with a bisubstrate analog (N1-acetylspermine-S-CoA).

Summary for 2JEV

• Entry DOI: 10.2210/pdb2jev/pdb
• Related: 2B3U 2B3V 2B4B 2B4D 2B58 2B5G 2F5I 2FXF 2G3T
• Descriptor: DIAMINE ACETYLTRANSFERASE 1, (3R)-27-AMINO-3-HYDROXY-2,2-DIMETHYL-4,8,14-TRIOXO-12-THIA-5,9,15,19,24-PENTAAZAHEPTACOS-1-YL [(2S,3R,4S,5S)-5-(6-AMINO-9H-PURIN-9-YL)-4-HYDROXY-3-(PHOSPHONOOXY)TETRAHYDROFURAN-2-YL]METHYL DIHYDROGEN DIPHOSPHATE (3 entities in total)
• Functional Keywords: acyltransferase, acetyltransferase, gcn5 related n-acetyltransferase, polyamine biosynthesis, gnat, spermine, spermidine, transferase, bisubstrate
• Biological source: HOMO SAPIENS (HUMAN)
• Total number of polymer chains: 2
• Total formula weight: 42680.32

Authors

Hegde, S.S.,Chandler, J.,Vetting, M.W.,Yu, M.,Blanchard, J.S. (deposition date: 2007-01-23, release date: 2007-06-05, Last modification date: 2023-12-13)

Primary citation

Hegde, S.S.,Chandler, J.,Vetting, M.W.,Yu, M.,Blanchard, J.S.
Mechanistic and Structural Analysis of Human Spermidine/Spermine N(1)-Acetyltransferase.
Biochemistry, 46:7187-, 2007

PubMed Abstract: The N1-acetylation of spermidine and spermine by spermidine/spermine acetyltransferase (SSAT) is a crucial step in the regulation of the cellular polyamine levels in eukaryotic cells. Altered polyamine levels are associated with a variety of cancers as well as other diseases, and key enzymes in the polyamine pathway, including SSAT, are being explored as potential therapeutic drug targets. We have expressed and purified human SSAT in Escherichia coli and characterized its kinetic and chemical mechanism. Initial velocity and inhibition studies support a random sequential mechanism for the enzyme. The bisubstrate analogue, N1-spermine-acetyl-coenzyme A, exhibited linear, competitive inhibition against both substrates with a true Ki of 6 nM. The pH-activity profile was bell-shaped, depending on the ionization state of two groups exhibiting apparent pKa values of 7.27 and 8.87. The three-dimensional crystal structure of SSAT with bound bisubstrate inhibitor was determined at 2.3 A resolution. The structure of the SSAT-spermine-acetyl-coenzyme A complex suggested that Tyr140 acts as general acid and Glu92, through one or more water molecules, acts as the general base during catalysis. On the basis of kinetic properties, pH dependence, and structural information, we propose an acid/base-assisted reaction catalyzed by SSAT, involving a ternary complex.

PubMed: 17516632
DOI: 10.1021/BI700256Z

Experimental method

X-RAY DIFFRACTION (2.3 Å)