title: Regulation of S-adenosylhomocysteine hydrolase by lysine acetylation.
abstract: S-Adenosylhomocysteine hydrolase (SAHH) is an NAD(+)-dependent tetrameric enzyme that catalyzes the breakdown of S-adenosylhomocysteine to adenosine and homocysteine and is important in cell growth and the regulation of gene expression. Loss of SAHH function can result in global inhibition of cellular methyltransferase enzymes because of high levels of S-adenosylhomocysteine. Prior proteomics studies have identified two SAHH acetylation sites at Lys(401) and Lys(408) but the impact of these post-translational modifications has not yet been determined. Here we use expressed protein ligation to produce semisynthetic SAHH acetylated at Lys(401) and Lys(408) and show that modification of either position negatively impacts the catalytic activity of SAHH. X-ray crystal structures of 408-acetylated SAHH and dually acetylated SAHH have been determined and reveal perturbations in the C-terminal hydrogen bonding patterns, a region of the protein important for NAD(+) binding. These crystal structures along with mutagenesis data suggest that such hydrogen bond perturbations are responsible for SAHH catalytic inhibition by acetylation. These results suggest how increased acetylation of SAHH may globally influence cellular methylation patterns.
authors.affiliation: From the Deptartments of Pharmacology and Molecular Sciences and.
authors.forename: Yun
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Biophysics and Biophysical Chemistry, The Johns Hopkins School of Medicine, Baltimore, Maryland 21205.
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Kavran
authors.affiliation: From the Deptartments of Pharmacology and Molecular Sciences and.
authors.forename: Zan
authors.initials: Z
authors.lastname: Chen
authors.affiliation: From the Deptartments of Pharmacology and Molecular Sciences and.
authors.forename: Kannan R
authors.initials: KR
authors.lastname: Karukurichi
authors.affiliation: From the Deptartments of Pharmacology and Molecular Sciences and Biophysics and Biophysical Chemistry, The Johns Hopkins School of Medicine, Baltimore, Maryland 21205.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Leahy
authors.affiliation: From the Deptartments of Pharmacology and Molecular Sciences and pcole@jhmi.edu.
authors.forename: Philip A
authors.initials: PA
authors.lastname: Cole
mesh_terms: D000107:Acetylation; D043383:Adenosylhomocysteinase / Q000378:metabolism*; D000595:Amino Acid Sequence; D002384:Catalysis; D018360:Crystallography, X-Ray; D006801:Humans; D006860:Hydrogen Bonding; D008239:Lysine / Q000378:metabolism*; D008745:Methylation; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009243:NAD / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013329:Structure-Activity Relationship
chemical_list: D011994:Recombinant Proteins; D009243:NAD; D043383:Adenosylhomocysteinase; D008239:Lysine
keywords: Enzyme; Peptides; Post-translational Modification (PTM); Protein Structure; X-ray Crystallography