title: Mycobacterium tuberculosis S-adenosyl-l-homocysteine hydrolase is negatively regulated by Ser/Thr phosphorylation.
abstract: S-Adenosylhomocysteine hydrolase (SahH) is known as an ubiquitous player in methylation-based process that maintains the intracellular S-adenosylhomocysteine (SAH) and S-adenosylmethionine (SAM) equilibrium. Given its crucial role in central metabolism in both eukaryotes and prokaryotes, it is assumed that SahH must be regulated, albeit little is known regarding molecular mechanisms governing its activity. We report here that SahH from Mycobacterium tuberculosis can be phosphorylated by mycobacterial Ser/Thr protein kinases and that phosphorylation negatively affects its enzymatic activity. Mass spectrometric analyses and site-directed mutagenesis identified Thr2 and Thr221 as the two phosphoacceptors. SahH_T2D, SahH_T221D and SahH_T2D/T221D, designed to mimic constitutive phosphorylation, exhibited markedly decreased activity compared to the wild-type enzyme. Both residues are fully conserved in other mycobacterial SahH orthologues, suggesting that SahH phosphorylation on Thr2 and Thr221 may represent a novel and presumably more general mechanism of regulation of the SAH/SAM balance in mycobacteria.
authors.affiliation: Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Université Montpellier 2, CNRS, UMR 5235, case 107, Place Eugène Bataillon, 34095 Montpellier Cedex 05, France.
authors.forename: Rosa Milagros
authors.initials: RM
authors.lastname: Corrales
authors.forename: Jade
authors.initials: J
authors.lastname: Leiba
authors.forename: Martin
authors.initials: M
authors.lastname: Cohen-Gonsaud
authors.forename: Virginie
authors.initials: V
authors.lastname: Molle
authors.forename: Laurent
authors.initials: L
authors.lastname: Kremer
mesh_terms: D043383:Adenosylhomocysteinase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009169:Mycobacterium tuberculosis / Q000201:enzymology*; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D017433:Protein Structure, Secondary; D012694:Serine / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D013912:Threonine / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D013912:Threonine; D012694:Serine; D017346:Protein Serine-Threonine Kinases; D043383:Adenosylhomocysteinase