caa a22 4500 378849700 CHVBK 20180305123320.0 cr unu---uuuuu 161128e20030127xx s 000 0 eng 10.1515/BC.2003.009 doi (NATIONALLICENCE)gruyter-10.1515/BC.2003.009 Caenorhabditis elegans S-AdenosylmethionineDecarboxylase Is Highly Stimulated byPutrescine But Exhibits a Low Specificity forActivator Binding [Elektronische Daten] [D. Ndjonka, A. Da'dara, R.D. Walter, K. Lüersen] S-Adenosylmethionine decarboxylase (AdoMetDC) is a key enzyme of the polyamine synthetic pathway providing decarboxylated S-adenosylmethionine for the formation of spermidine and spermine, respectively. The catalytic activity of the AdoMetDC from the free living nematode Caenorhabditis elegans highly depends on the presence of an activator molecule. Putrescine, a well-known stimulator of mammalian AdoMetDC activity, enhances the catalytic activity of the nematode enzyme 350-fold. Putrescine stimulation is discussed as a regulatory mechanism to relate putrescine abundance with the synthesis of spermidine and spermine. In contrast to any other known AdoMetDC, spermidine and spermine also represent significant activators of the nematode enzyme. However, the biological significance of the observed stimulation by these higher polyamines is unclear. Although C. elegans AdoMetDC exhibits a low specificity toward activator molecules, the amino acid residues that were shown to be involved in putrescine binding of the human enzyme are conserved in the nematode enzyme. Exchanging these residues by site-directed mutagenesis indicates that at least three residues, Thr192, Glu194 and Glu274, most likely contribute to activator binding in the C. elegans AdoMetDC. Interestingly, the mutant Glu194Gln exhibits a 100-fold enhanced basal activity in the absence of any stimulator, suggesting that this mutant protein mimics the conformational change usually induced by activator molecules. Furthermore, site directed mutagenesis revealed that at least Glu33, Ser83, Arg91and Lys95are involved in posttranslational processing of C. elegans AdoMetDC. Copyright © 2003 by Walter de Gruyter GmbH & Co. KG Biochemistry nationallicence Molecular biology nationallicence Cellular biology nationallicence Ndjonka D. aut Da'dara A. aut Walter R.D. aut Lüersen K. aut Biological Chemistry Walter de Gruyter 384/1(2003-01-27), 83-91 1431-6730 384:1<83 2003 384 bchm https://doi.org/10.1515/BC.2003.009 text/html Onlinezugriff via DOI 1 research article jats NATIONALLICENCE 856 40 https://doi.org/10.1515/BC.2003.009 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Ndjonka D. aut NATIONALLICENCE 700 1- Da'dara A. aut NATIONALLICENCE 700 1- Walter R.D. aut NATIONALLICENCE 700 1- Lüersen K. aut NATIONALLICENCE 773 0- Biological Chemistry Walter de Gruyter 384/1(2003-01-27), 83-91 1431-6730 384:1<83 2003 384 bchm CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-gruyter