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Mathias Ziegler

Publications and source records attributed to Mathias Ziegler.

9 recordsLinked to original sources
PubMed2006

Time sensing by NAADP receptors.

NAADP (nicotinic acid-adenine dinucleotide phosphate) is a newly described intracellular messenger molecule that mediates Ca2+ increases in a variety of cells. However, little is known of the mechanism whereby ligand binding regulates the target protein. We report in the present paper that NAADP receptors from sea urchin eggs undergo an unusual stabilization process that appears to be dependent upon the time during which receptors are exposed to their ligand. We demonstrate that receptors 'tagged' with NAADP for short periods were more readily dissociated following subsequent delipidation than those labelled for longer. Stabilization of NAADP receptors by their ligand was delayed relative to ligand association taking on the order of minutes to develop at picomolar concentrations. The stabilizing effects of NAADP did not require cytosolic factors or the continued presence of NAADP and persisted upon solubilization. NAADP receptors, however, failed to stabilize at reduced temperature. We conclude that NAADP receptors possess a simple molecular memory endowing them with the remarkable ability to detect the duration of their activation.

Animals↗
PubMed2005

Subcellular compartmentation and differential catalytic properties of the three human nicotinamide mononucleotide adenylyltransferase isoforms.

Nicotinamide mononucleotide adenylyltransferase (NMNAT) is the central enzyme of the NAD biosynthetic pathway. Three human NMNAT isoforms have recently been identified, but isoform-specific functions are presently unknown, although a tissue-specific role has been suggested. Analyses of the subcellular localization confirmed NMNAT1 to be a nuclear protein, whereas NMNAT2 and -3 were localized to the Golgi complex and the mitochondria, respectively. This differential subcellular localization points to an organelle-specific, nonredundant function of each of the three proteins. Comparison of the kinetic properties showed that particularly NMNAT3 exhibits a high tolerance toward substrate modifications. Moreover, as opposed to preferred NAD+ synthesis by NMNAT1, the other two isoforms could also form NADH directly from the reduced nicotinamide mononucleotide, supporting a hitherto unknown pathway of NAD generation. A variety of physiological intermediates was tested and exerted only minor influence on the catalytic activities of the NMNATs. However, gallotannin was found to be a potent inhibitor, thereby compromising its use as a specific inhibitor of poly-ADP-ribose glycohydrolase. The presence of substrate-specific and independent nuclear, mitochondrial, and Golgi-specific NAD biosynthetic pathways is opposed to the assumption of a general cellular NAD pool. Their existence appears to be consistent with important compartment-specific functions rather than to reflect simple functional redundance.

Adenosine Triphosphate↗
PubMed2005

Poly(ADP-ribosylation) and genomic stability.

Poly(ADP-ribose) polymerases (PARPs) catalyze the synthesis of ADP-ribose polymers and attach them to specific target proteins. To date, 6 members of this protein family in humans have been characterized. The best-known PARP, PARP-1, is located within the nucleus and has a major function in DNA repair but also in the execution of cell death pathways. Other PARP enzymes appear to carry out highly specific functions. Most prominently, the tankyrases modify telomere-binding proteins and thereby regulate telomere maintenance. Since only a single enzyme, poly(ADP-ribose) glycohydrolase (PARG), has been identified, which degrades poly(ADP-ribose), it is expected that this protein has important roles in PARP-mediated regulatory processes. This review summarizes recent observations indicating that poly(ADP-ribosylation) represents a major mechanism to regulate genomic stability both when DNA is damaged by exogenous agents and during cell division.

Adenosine Diphosphate Ribose↗
PubMed2004

NAD+ surfaces again.

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Adenosine Diphosphate Ribose↗
PubMed2004

The new life of a centenarian: signalling functions of NAD(P).

Since the beginning of the last century, seminal discoveries have identified pyridine nucleotides as the major redox carriers in all organisms. Recent research has unravelled an unexpectedly wide array of signalling pathways that involve nicotinamide adenine dinucleotide (NAD) and its phosphorylated form, NADP. NAD serves as substrate for protein modification including protein deacetylation, and mono- and poly-ADP-ribosylation. Both NAD and NADP represent precursors of intracellular calcium-mobilizing molecules. It is now beyond doubt that NAD(P)-mediated signal transduction does not merely regulate metabolic pathways, but might hold a key position in the control of fundamental cellular processes. The comprehensive molecular characterization of NAD biosynthetic pathways over the past few years has further extended the understanding of the multiple roles of pyridine nucleotides in cell biology.

Adenosine Diphosphate Ribose↗
PubMed2003

ATP-dependent selection between single nucleotide and long patch base excision repair.

DNA base excision repair (BER) constitutes a major mechanism to restore the integrity of the genome following modifications of nucleobases. Although it is well established that poly(ADP-ribosylation) facilitates BER, the mechanism of this stimulation has remained unknown. Previous observations suggested that poly(ADP-ribose), which is synthesised from NAD(+), could serve as a unique source of ATP required for the ligation step in BER. This pathway of ATP generation is thought to compensate ATP shortage and relies on the release of pyrophosphate during DNA repair synthesis. Here, we present evidence that, in situations of cellular energy depletion, the synthesis of poly(ADP-ribose) is indeed stimulated. Simultaneously, single nucleotide repair is reduced. Rather, the number of nucleotides incorporated by DNA polymerase beta (Pol beta) during DNA repair synthesis is increased. Using a reconstituted system including the recombinant BER proteins Pol beta, AP endonuclease 1 (APE 1), X-ray repair cross-complementing group-1 (XRCC1), DNA ligase III (Lig III), flap endonuclease 1 (FEN 1), and poly(ADP-ribose) polymerase-1 (PARP-1), it is demonstrated that in the absence of ATP, both long patch DNA synthesis by Pol beta and poly(ADP-ribosylation) catalysed by PARP-1 are stimulated. Consequently, the preferred use of either long patch or single nucleotide BER depends on the availability of ATP. It is proposed that long patch BER is required for ATP generation from poly(ADP-ribose) and, therefore, predominant under conditions of ATP shortage.

Adenosine Triphosphate↗
PubMed2002

Crystal structure of human nicotinamide mononucleotide adenylyltransferase in complex with NMN.

The final step in the biosynthesis of nicotinamide-adenine dinucleotide, a major coenzyme in cellular redox reactions and involved in intracellular signaling, is catalyzed by the enzyme nicotinamide mononucleotide adenylyltransferase (NMNAT). The X-ray structure of human NMNAT in complex with nicotinamide mononucleotide was solved by the single-wavelength anomalous dispersion method at a resolution of 2.9 A. Human NMNAT is a symmetric hexamer whose subunit is formed by a large six-stranded parallel beta-sheet with helices on both sides. Human NMNAT displays a different oligomerization compared to the archaeal enzyme. The protein-nicotinamide mononucleotide interaction pattern provides insight into ligand binding in the human enzyme.

Amino Acid Sequence↗
PubMed2001

Crystallization and preliminary X-ray analysis of human nicotinamide mononucleotide adenylyltransferase (NMNAT).

Nicotinamide mononucleotide adenylyltransferase catalyses the final step in the synthesis of nicotinamide-adenine dinucleotide (NAD(+)) by transferring the adenylyl moiety of ATP to nicotinamide mononucleotide (NMN) with the release of pyrophosphate. The human enzyme was crystallized in the presence of NAD(+). Crystals grew in the orthorhombic space group C222(1), with unit-cell parameters a = 140.3, b = 235.5, c = 89.3 A, and diffract to a maximum resolution of 3.0 A. Packing considerations suggest a trimer or higher multimer to be present in the asymmetric unit of the crystal. Two archaeal homologues have been described to form hexamers.

Amino Acid Sequence↗