Title

The first agmatine/cadaverine aminopropyl transferase: Biochemical and structural characterization of an enzyme involved in polyamine biosynthesis in the hyperthermophilic archaeon Pyrococcus furiosus

Document Type

Article

Publication Date

2007

Abstract

We report here the characterization of the first agmatine/cadaverine aminopropyl transferase (ACAPT), the enzyme responsible for polyamine biosynthesis from an archaeon. The gene PF0127 encoding ACAPT in the hyperthermophile Pyrococcus furiosus was cloned and expressed in Escherichia coli, and the recombinant protein was purified to homogeneity. P. furiosus ACAPT is a homodimer of 65 kDa. The broad substrate specificity of the enzyme toward the amine acceptors is unique, as agmatine, 1,3-diaminopropane, putrescine, cadaverine, and sym-nor-spermidine all serve as substrates. While maximal catalytic activity was observed with cadaverine, agmatine was the preferred substrate on the basis of the kcat/Km value. P. furiosus ACAPT is thermoactive and thermostable with an apparent melting temperature of 108°C that increases to 112°C in the presence of cadaverine. Limited proteolysis indicated that the only proteolytic cleavage site is localized in the C-terminal region and that the C-terminal peptide is not necessary for the integrity of the active site. The crystal structure of the enzyme determined to 1.8-Å resolution confirmed its dimeric nature and provided insight into the proteolytic analyses as well as into mechanisms of thermal stability. Analysis of the polyamine content of P. füriosus showed that spermidine, cadaverine, and sym-nor-spermidine are the major components, with small amounts of sym-nor-spermine and N-(3-aminopropyl)cadaverine (APC). This is the first report in Archaea of an unusual polyamine APC that is proposed to play a role in stress adaptation. Copyright © 2007, American Society for Microbiology. All Rights Reserved.

Publication Title

Journal of Bacteriology

Volume

189

Issue

16

First Page

6057

Last Page

6067

Comments

This article was published in Journal of Bacteriology, Volume 189, Issue 16, Pages 6057-6067.

The published version is available at http://dx.doi.org/10.1128/JB.00151-07.

Copyright © 2007 ASM.

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