title: The Major Protein Arginine Methyltransferase inTrypanosoma bruceiFunctions as an Enzyme-Prozyme Complex.
abstract: Prozymes are catalytically inactive enzyme paralogs that dramatically stimulate the function of weakly active enzymes through complex formation. The two prozymes described to date reside in the polyamine biosynthesis pathway of the human parasiteTrypanosoma brucei, an early branching eukaryote that lacks transcriptional regulation and regulates its proteome through posttranscriptional and posttranslational means. Arginine methylation is a common posttranslational modification in eukaryotes catalyzed by protein arginine methyltransferases (PRMTs) that are typically thought to function as homodimers. We demonstrate that a majorT. bruceiPRMT,TbPRMT1, functions as a heterotetrameric enzyme-prozyme pair. The inactive PRMT paralog,TbPRMT1PRO, is essential for catalytic activity of theTbPRMT1ENZsubunit. Mutational analysis definitively demonstrates that TbPRMT1ENZis the cofactor-binding subunit and carries all catalytic activity of the complex. Our results are the first demonstration of an obligate heteromeric PRMT, and they suggest that enzyme-prozyme organization is expanded in trypanosomes as a posttranslational means of enzyme regulation.
authors.affiliation: From the Department of Microbiology and Immunology, Witebsky Center for Microbial Pathogenesis and Immunology, and Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York 14214.
authors.forename: Lucie
authors.initials: L
authors.lastname: Kafková
authors.affiliation: the Laboratory of Cell Biology, The Rockefeller University, New York, New York 10065, and.
authors.forename: Erik W
authors.initials: EW
authors.lastname: Debler
authors.affiliation: From the Department of Microbiology and Immunology, Witebsky Center for Microbial Pathogenesis and Immunology, and Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York 14214.
authors.forename: John C
authors.initials: JC
authors.lastname: Fisk
authors.affiliation: the Department of Chemistry and Biochemistry and The Molecular Biology Institute, UCLA, Los Angeles, California 90095.
authors.forename: Kanishk
authors.initials: K
authors.lastname: Jain
authors.affiliation: the Department of Chemistry and Biochemistry and The Molecular Biology Institute, UCLA, Los Angeles, California 90095.
authors.forename: Steven G
authors.initials: SG
authors.lastname: Clarke
authors.affiliation: From the Department of Microbiology and Immunology, Witebsky Center for Microbial Pathogenesis and Immunology, and Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York 14214, lread@buffalo.edu.
authors.forename: Laurie K
authors.initials: LK
authors.lastname: Read
mesh_terms: D000595:Amino Acid Sequence; D001704:Biopolymers / Q000378:metabolism; D020134:Catalytic Domain; D002460:Cell Line; D004795:Enzyme Stability; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D011484:Protein-Arginine N-Methyltransferases / Q000737:chemistry / Q000378:metabolism*; D015800:Protozoan Proteins / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D014346:Trypanosoma brucei brucei / Q000201:enzymology*
chemical_list: D001704:Biopolymers; D015800:Protozoan Proteins; D011484:Protein-Arginine N-Methyltransferases
keywords: PRMT; Trypanosoma brucei; allosteric regulation; arginine methylation; post-translational modification (PTM); protein methylation; prozyme; trypanosome