Substrate-Induced Allosteric Change in the Quaternary Structure of the Spermidine N-Acetyltransferase SpeG
The spermidine N-acetyltransferase SpeG is a dodecameric enzyme that catalyzes the transfer of an acetyl group from acetyl coenzyme A to polyamines such as spermidine and spermine. SpeG has an allosteric polyamine-binding site and acetylating polyamines regulate their intracellular concentrations. The structures of SpeG from Vibrio cholerae in complexes with polyamines and cofactor have been characterized earlier. Here, we present the dodecameric structure of SpeG from V. cholerae in a ligand-free form in three different conformational states: open, intermediate and closed. All structures were crystallized in C2 space group symmetry and contain six monomers in the asymmetric unit cell. Two hexamers related by crystallographic 2-fold symmetry form the SpeG dodecamer. The open and intermediate states have a unique open dodecameric ring. This SpeG dodecamer is asymmetric except for the one 2-fold axis and is unlike any known dodecameric structure. Using a fluorescence thermal shift assay, size-exclusion chromatography with multi-angle light scattering, small-angle X-ray scattering analysis, negative-stain electron microscopy and structural analysis, we demonstrate that this unique open dodecameric state exists in solution. As a result, our combined results indicate that polyamines trigger conformational changes and induce the symmetric closed dodecameric state of the protein when they bind to their allosteric sites.
- Research Organization:
- Argonne National Laboratory (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Grant/Contract Number:
- AC02-06CH11357
- OSTI ID:
- 1374483
- Alternate ID(s):
- OSTI ID: 1248371
- Journal Information:
- Journal of Molecular Biology, Journal Name: Journal of Molecular Biology Vol. 427 Journal Issue: 22; ISSN 0022-2836
- Publisher:
- ElsevierCopyright Statement
- Country of Publication:
- United Kingdom
- Language:
- English
Web of Science
Analysis of crystalline and solution states of ligand-free spermidine N -acetyltransferase (SpeG) from Escherichia coli
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journal | May 2019 |
The spermidine acetyltransferase SpeG regulates transcription of the small RNA rprA
|
journal | December 2018 |
Structure and Functional Diversity of GCN5-Related N-Acetyltransferases (GNAT)
|
journal | June 2016 |
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