196,971 research outputs found
Arylsulfatase G, a novel lysosomal sulfatase
No full textFrese M-A, Schulz S, Dierks T. Arylsulfatase G, a novel lysosomal sulfatase. JOURNAL OF BIOLOGICAL CHEMISTRY. 2008;283(17):11388-11395.The sulfatases constitute a conserved family of enzymes that specifically hydrolyze sulfate esters in a wide variety of substrates such as glycosaminoglycans, steroid sulfates, or sulfolipids. By modifying the sulfation state of their substrates, sulfatases play a key role in the control of physiological processes, including cellular degradation, cell signaling, and hormone regulation. The loss of sulfatase activity has been linked with various severe pathophysiological conditions such as lysosomal storage disorders, developmental abnormalities, or cancer. A novel member of this family, arylsulfatase G (ASG), was initially described as an enzyme lacking in vitro arylsulfatase activity and localizing to the endoplasmic reticulum. Contrary to these results, we demonstrate here that ASG does indeed have arylsulfatase activity toward different pseudosubstrates like p-nitrocatechol sulfate and 4-methylumbelliferyl sulfate. The activity of ASG depends on the Cys-84 residue that is predicted to be post-translationally converted to the critical active site C-alpha-formylglycine. Phosphate acts as a strong, competitive ASG inhibitor. ASG is active as an unprocessed 63-kDa monomer and shows an acidic pH optimum as typically seen for lysosomal sulfatases. In transfected cells, ASG accumulates within lysosomes as indicated by indirect immunofluorescence microscopy. Furthermore, ASG is a glycoprotein that binds specifically to mannose 6-phosphate receptors, corroborating its lysosomal localization. ARSG mRNA expression was found to be tissue-specific with highest expression in liver, kidney, and pancreas, suggesting a metabolic role of ASG that might be associated with a so far non-classified lysosomal storage disorder
Characterization of posttranslational formylglycine formation by luminal components of the endoplasmic reticulum
No full textFey J, Balleininger M, Borissenko LV, Schmidt B, Figura von K, Dierks T. Characterization of posttranslational formylglycine formation by luminal components of the endoplasmic reticulum. JOURNAL OF BIOLOGICAL CHEMISTRY. 2001;276(50):47021-47028.C-alpha-formylglycine is the key catalytic residue in the active site of sulfatases. In eukaryotes formylglycine is generated during or immediately after sulfatase translocation into the endoplasmic reticulum by oxidation of a specific cysteine residue. We established an in vitro assay that allowed us to measure formylglycine modification independent of protein translocation. The modifying enzyme was recovered in a microsomal detergent extract. As a substrate we used ribosome-associated nascent chain complexes comprising in vitro synthesized sulfatase fragments that were released from the ribosomes by puromycin. Formylglycine modification was highly efficient and did not require a signal sequence in the substrate polypeptide. Ribosome association helped to maintain the modification competence of nascent chains but only after their release efficient modification occurred. The modifying machinery consists of soluble components of the endoplasmic reticulum lumen, as shown by differential extraction of microsomes. The in vitro assay can be performed under kinetically controlled conditions. The activation energy for formylglycine formation is 61 kJ/mol, and the pH optimum is approximate to 10. The activity is sensitive to the SH/SS equilibrium and is stimulated by Ca2+. Formylglycine formation is efficiently inhibited by a synthetic sulfatase peptide representing the sequence directing formylglycine modification. The established assay system should make possible the biochemical identification of the modifying enzyme
Sulf loss influences N-, 2-O-, and 6-O-sulfation of multiple heparan sulfate proteoglycans and modulates fibroblast growth factor signaling
No full textLamanna WC, Frese M-A, Balleininger M, Dierks T. Sulf loss influences N-, 2-O-, and 6-O-sulfation of multiple heparan sulfate proteoglycans and modulates fibroblast growth factor signaling. JOURNAL OF BIOLOGICAL CHEMISTRY. 2008;283(41):27724-27735.Sulf1 and Sulf2 are two heparan sulfate 6-O-endosulfatases that regulate the activity of multiple growth factors, such as fibroblast growth factor and Wnt, and are essential for mammalian development and survival. In this study, the mammalian Sulfs were functionally characterized using overexpressing cell lines, in vitro enzyme assays, and in vivo Sulf knock-out cell models. Analysis of subcellular Sulf localization revealed significant differences in enzyme secretion and detergent solubility between the human isoforms and their previously characterized quail orthologs. Further, the activity of the Sulfs toward their native heparan sulfate substrates was determined in vitro, demonstrating restricted specificity for S-domain-associated 6S disaccharides and an inability to modify transition zone-associated UA-GlcNAc( 6S). Analysis of heparan sulfate composition from different cell surface, shed, glycosylphosphatidylinositol- anchored and extracellular matrix proteoglycan fractions of Sulf knock-out cell lines established differential effects of Sulf1 and/or Sulf2 loss on nonsubstrate N-, 2-O-, and 6-O-sulfate groups. These findings indicate a dynamic influence of Sulf deficiency on the HS biosynthetic machinery. Real time PCR analysis substantiated differential expression of the Hs2st and Hs6st heparan sulfate sulfotransferase enzymes in the Sulf knock-out cell lines. Functionally, the changes in heparan sulfate sulfation resulting from Sulf loss were shown to elicit significant effects on fibroblast growth factor signaling. Taken together, this study implicates that the Sulfs are involved in a potential cellular feed-back mechanism, in which they edit the sulfation of multiple heparan sulfate proteoglycans, thereby regulating cellular signaling and modulating the expression of heparan sulfate biosynthetic enzymes
Channel properties of mitochondrial carriers
No full textDierks T, Stappen R, Krämer R. Channel properties of mitochondrial carriers. In: Forte M, Colombini M, eds. Molecular Biology of Mitochondrial Transport Systems. Nato ASI Series. Vol H83. Berlin: Springer; 1994: 117-129
Die Rechtsform des CFR und die Frage nach der Kompetenz
No full textHähnchen S. Die Rechtsform des CFR und die Frage nach der Kompetenz. In: Schmidt-Kessel M, Dierks T, eds. Der Gemeinsame Referenzrahmen. München: Sellier European Law Publ.; 2009: 147-171
ERp44 mediates a thiol-independent retention of formylglycine-generating enzyme in the endoplasmic reticulum
No full textMariappan M, Radhakrishnan K, Dierks T, Schmidt B, von Figura K. ERp44 mediates a thiol-independent retention of formylglycine-generating enzyme in the endoplasmic reticulum. JOURNAL OF BIOLOGICAL CHEMISTRY. 2008;283(10):6375-6383.Inside the endoplasmic reticulum (ER) formylglycine-generating enzyme (FGE) catalyzes in newly synthesized sulfatases the post-translational oxidation of a specific cysteine. Thereby formylglycine is generated, which is essential for sulfatase activity. Here we show that ERp44 interacts with FGE forming heterodimeric and, to a lesser extent, also heterotetrameric and octameric complexes, which are stabilized through disulfide bonding between cysteine 29 of ERp44 and cysteines 50 and 52 in the N-terminal region of FGE. ERp44 mediates FGE retrieval to the ER via its C-terminal RDEL signal. Increasing ERp44 levels by overexpression enhances and decreasing ERp44 levels by silencing reduces ER retention of FGE. Suppressing disulfide bonding by mutating the critical cysteines neither abrogates ERp44.FGE complex formation nor interferes with ERp44-mediated retention of FGE, indicating that noncovalent interactions between ERp44 and FGE are sufficient to mediate ER retention. The N-terminal region of FGE harboring Cys(50) and Cys(52) is dispensible for catalytic activity in vitro but required for FGE-mediated activation of sulfatases in vivo. This in vivo activity is affected neither by overexpression nor by silencing of ERp44, indicating that a further ER component interacting with the N-terminal extension of FGE is critical for sulfatase activation
Experimental studies of the adsorption of oxygen and nitric oxide at Ni(100)
No full textVolkmer M, Nolting K, Fecher GH, Dierks B, Heinzmann U. Experimental studies of the adsorption of oxygen and nitric oxide at Ni(100). Vacuum. 1990;41(1-3):109-111
Formylglycine Aldehyde Tag-Protein Engineering through a Novel Post-translational Modification
No full textFrese M-A, Dierks T. Formylglycine Aldehyde Tag-Protein Engineering through a Novel Post-translational Modification. CHEMBIOCHEM. 2009;10(3):425-427.Oxidation of a specific cysteine residue to C(alpha)-formylglycine is a novel post-translational modification that is directed by a short recognition motif commonly found in pro- and eukaryotic sulfatases. As recently shown by C. Bertozzi and co-workers, this system can be employed in protein engineering to equip proteins with genetically encoded aldehyde tags for site-specific labeling, conjugation and immobilization
Molecular basis for multiple sulfatase deficiency and mechanism for formylglycine generation of the human formylglycine-generating enzyme
No full textDierks T, Dickmanns A, Preusser-Kunze A, et al. Molecular basis for multiple sulfatase deficiency and mechanism for formylglycine generation of the human formylglycine-generating enzyme. CELL. 2005;121(4):541-552.Sulfatases are enzymes essential for degradation and remodeling of sulfate esters. Formylglycine (FGly), the key catalytic residue in the active site, is unique to sulfatases. In higher eukaryotes, FGly is generated from a cysteine precursor by the FGly-generating enzyme (FGE). Inactivity of FGE results in multiple sulfatase deficiency (MSD), a fatal autosomal recessive syndrome. Based on the crystal structure, we report that FGE is a single-domain monomer with a surprising paucity of secondary structure and adopts a unique fold. The effect of all 18 missense mutations found in MSD patients is explained by the FGE structure, providing a molecular basis of MSD. The catalytic mechanism of FGly generation was elucidated by six high-resolution structures of FGE in different redox environments. The structures allow formulation of a novel oxygenase mechanism whereby FGE utilizes molecular oxygen to generate FGly via a cysteine sulfenic acid intermediate
Autonomie und Patientenberatung
No full textDierks M-L, Schaeffer D. Autonomie und Patientenberatung. In: Rosenbrock R, Hartung S, eds. Handbuch Partizipation und Gesundheit. Bern: Huber; 2012: 285-295
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