X-ray structure of yeast hal2p, a major target of lithium and sodium toxicity, and identification of framework interactions determining cation sensitivity

Albert, Armando; Yenush, Lynne; Gil-Mascarell, M.R.; Rodrı́guez, Pedro L.; Patel, Sangita; Martı́nez-Ripoll, M.; Blundell, Tom L.; Serrano, Ramón

doi:10.1006/jmbi.1999.3408

Cited by 66 publications

(101 citation statements)

References 42 publications

(69 reference statements)

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“…For example, the concentration of Na ϩ is kept relatively low in many cell types, while K ϩ is found at much higher concentrations, since some metabolic enzymes are known to be sensitive to Na ϩ as well as Li ϩ ions (1,13,34,35). Although NaCl was used as an osmolyte to isolate and characterize mutants of the osmosensing Hog1 SAPK in S. cerevisiae, we noticed that the homologous SAPK in S. pombe, Spc1, is required for cellular resistance to Na ϩ , independently of its role in the osmostress response.…”

Section: Discussionmentioning

confidence: 99%

Response of Fission Yeast to Toxic Cations Involves Cooperative Action of the Stress-Activated Protein Kinase Spc1/Sty1 and the Hal4 Protein Kinase

Shimada

Morishita

et al. 2005

Molecular and Cellular Biology

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Section: Discussionmentioning

confidence: 99%

Response of Fission Yeast to Toxic Cations Involves Cooperative Action of the Stress-Activated Protein Kinase Spc1/Sty1 and the Hal4 Protein Kinase

Shimada

Morishita

et al. 2005

Molecular and Cellular Biology

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“…The three conserved motifs (motifs A, B, and C) of the protein family of magnesium-dependent, lithium-sensitive phosphatases were present (4,14,28). These motifs contained all critical residues involved in substrate and metal binding (data not shown), as defined for Hal2p of yeast (2,19).…”

Section: Resultsmentioning

confidence: 93%

“…Hal2p and Tol1 from yeast and Sal1 from plants are all highly sensitive to Li ϩ and Na ϩ , while HalA and AtAHL are much less sensitive to these ions (Table 2). Structural analysis using X-ray crystallography of Hal2p from yeast indicates that lithium ions bind to the ternary complex formed by Hal2p, magnesium, and PAP and that they exert their inhibitory effect by blocking the release of the products of PAP hydrolysis from the active site (2,19). The structural basis of lower sensitivity of HalA and AtAHL is unknown, as the residues of site 2 of Hal2p involved in lithium binding are identically conserved in these two proteins.…”

Section: Discussionmentioning

confidence: 99%

A Lithium-Sensitive and Sodium-Tolerant 3′-Phosphoadenosine-5′-Phosphatase Encoded by halA from the Cyanobacterium Arthrospira platensis Is Closely Related to Its Counterparts from Yeasts and Plants

Zhang

Zou

Bao

et al. 2006

Appl Environ Microbiol

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3-Phosphoadenosine-5-phosphatase (PAPase) is required for the removal of toxic 3-phosphoadenosine-5-phosphate (PAP) produced during sulfur assimilation in various eukaryotic organisms. This enzyme is a well-known target of lithium and sodium toxicity and has been used for the production of salt-resistant transgenic plants. In addition, PAPase has also been proposed as a target in the treatment of manic-depressive patients. One gene, halA, which could encode a protein closely related to the PAPases of yeasts and plants, was identified from the cyanobacterium Arthrospira (Spirulina) platensis. Phylogenic analysis indicated that proteins related to PAPases from several cyanobacteria were found in different clades, suggesting multiple origins of PAPases in cyanobacteria. The HalA polypeptide from A. platensis was overproduced in Escherichia coli and used for the characterization of its biochemical properties. HalA was dependent on Mg 2؉ for its activity and could use PAP or 3-phosphoadenosine-5-phosphosulfate as a substrate. HalA is sensitive to Li ؉ (50% inhibitory concentration [IC 50 ] ‫؍‬ 3.6 mM) but only slightly sensitive to Na ؉ (IC 50 ‫؍‬ 600 mM). The salt sensitivity of HalA was thus different from that of most of its eukaryotic counterparts, which are much more sensitive to both Li ؉ and Na ؉ , but was comparable to the PAPase AtAHL (Hal2p-like protein) from Arabidopsis thaliana. The properties of HalA could help us to understand the structure-function relationship underlying the salt sensitivity of PAPases. The expression of halA improved the Li ؉ tolerance of E. coli, suggesting that the sulfur-assimilating pathway is a likely target of salt toxicity in bacteria as well.

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“…The inhibitory properties that monovalent cations, such as lithium and sodium, exert in the hydrolysis of phosphodiester bonds has been reported for other phosphoryl-transfer enzymes, such as the Mg 2+ -dependent phosphatases (Albert et al 2000;Patel et al 2002). Exonucleases and phosphatases share some catalytic properties, in particular the requirement of divalent metal cations and the initiation of the hydrolytic reaction by a nucleophilic attack on a water molecule (Brautigam et al 1999a,b;Hamdan et al 2002b;Patel et al 2002).…”

Section: Inhibition Of Trex1 By Monovalent Cationsmentioning

confidence: 99%

Structural and biochemical studies of TREX1 inhibition by metals. Identification of a new active histidine conserved in DEDDh exonucleases

et al. 2008

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TREX1 is the major exonuclease in mammalian cells, exhibiting the highest level of activity with a 39!59 activity. This exonuclease is responsible in humans for Aicardi-Goutières syndrome and for an autosomal dominant retinal vasculopathy with cerebral leukodystrophy. In addition, this enzyme is associated with systemic lupus erythematosus. TREX1 belongs to the exonuclease DEDDh family, whose members display low levels of sequence identity, while possessing a common fold and active site organization. For these exonucleases, a catalytic mechanism has been proposed that involves two divalent metal ions bound to the DEDD motif. Here we studied the interaction of TREX1 with the monovalent cations lithium and sodium. We demonstrate that these metals inhibit the exonucleolytic activity of TREX1, as measured by the classical gel method, as well as by a new technique developed for monitoring the real-time exonuclease reaction. The X-ray structures of the enzyme in complex with these two cations and with a nucleotide, a product of the exonuclease reaction, were determined at 2.1 Å and 2.3 Å , respectively. A comparison with the structures of the active complexes (in the presence of magnesium or manganese) explains that the inhibition mechanism is caused by the noncatalytic metals competing with distinct affinities for the two metal-binding sites and inducing subtle rearrangements in active centers. Our analysis also reveals that a histidine residue (His124), highly conserved in the DEDDh family, is involved in the activity of TREX1, as confirmed by mutational studies. Our results shed further light on the mechanism of activity of the DEDEh family of exonucleases.Keywords: exonucleases; TREX1; DEDDh family; structure; enzymatic activityThe 39!59 exonucleases play a crucial role in many biological processes by removing nucleotides at the 39 termini from DNA ends, which must then be remodeled in order to prevent the formation of aberrant structures. The 39!59 exonucleases were initially found as proofreading enzymes associated with DNA polymerases. However, in recent years several eukaryotic 39!59 exonucleases, such as p53, the Werner syndrome protein (WRN), and MRE11, 3 These two authors contributed equally to this work.

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X-ray structure of yeast hal2p, a major target of lithium and sodium toxicity, and identification of framework interactions determining cation sensitivity

Cited by 66 publications

References 42 publications

Response of Fission Yeast to Toxic Cations Involves Cooperative Action of the Stress-Activated Protein Kinase Spc1/Sty1 and the Hal4 Protein Kinase

Response of Fission Yeast to Toxic Cations Involves Cooperative Action of the Stress-Activated Protein Kinase Spc1/Sty1 and the Hal4 Protein Kinase

A Lithium-Sensitive and Sodium-Tolerant 3′-Phosphoadenosine-5′-Phosphatase Encoded by halA from the Cyanobacterium Arthrospira platensis Is Closely Related to Its Counterparts from Yeasts and Plants

Structural and biochemical studies of TREX1 inhibition by metals. Identification of a new active histidine conserved in DEDDh exonucleases

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