title: Identification and characterization of plant agmatine iminohydrolase, the last missing link in polyamine biosynthesis of plants.
abstract: The cloning, expression and characterization of plant agmatine iminohydrolase (AIH, also known as agmatine deiminase, EC 3.5.3.12) is described. Recombinant AIH of Arabidopsis thaliana forms dimers and catalyzes the specific conversion of agmatine to N-carbamoylputrescine and ammonia. Biochemical data suggested that cysteine side chains are involved in catalysis. However, site-directed mutagenesis of the two highly conserved cysteine residues of AIH showed that these cysteines are important but not essential for activity, arguing against a thioester substrate-enzyme intermediate during catalysis. This work represents the completion of the cloning of the arginine decarboxylase pathway genes of higher plants.
authors.affiliation: Department of Plant Physiology, Ruhr-Universität, Universitätsstr. 150, D-44801 Bochum, Germany.
authors.forename: Tim
authors.initials: T
authors.lastname: Janowitz
authors.forename: Helmut
authors.initials: H
authors.lastname: Kneifel
authors.forename: Markus
authors.initials: M
authors.lastname: Piotrowski
mesh_terms: D000641:Ammonia / Q000737:chemistry; D017360:Arabidopsis / Q000378:metabolism; D001120:Arginine / Q000737:chemistry; D002384:Catalysis; D020134:Catalytic Domain; D003001:Cloning, Molecular; D003545:Cysteine / Q000737:chemistry; D019281:Dimerization; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D006867:Hydrolases / Q000737:chemistry* / Q000276:immunology; D006868:Hydrolysis; D008956:Models, Chemical; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010944:Plants / Q000201:enzymology*; D011073:Polyamines; D011485:Protein Binding; D011700:Putrescine / Q000031:analogs & derivatives* / Q000737:chemistry; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D013997:Time Factors
chemical_list: D011073:Polyamines; D011994:Recombinant Proteins; D000641:Ammonia; D001120:Arginine; D006867:Hydrolases; C019626:agmatine deiminase; D003545:Cysteine; C024563:N-carbamoylputrescine; D011700:Putrescine