Mn(2+) transport by Ca(2+) -ATPase of sarcoplasmic reticulum.

Ca(2+) -ATPase of sarcoplasmic reticulum is known to pump Mn(2+) in addition to Ca(2+) , but whether its transport mechanism is identical to that of Ca(2+) is ambiguous. To clarify, we examined, by atomic absorption spectroscopy, competition between Mn(2+) and Ca(2+) in active transport using vesicles of sarcoplasmic reticulum (SR). Here, we demonstrate that Ca(2+) -ATPase transports Ca(2+) and Mn(2+) concomitantly but has a much lower affinity for Mn(2+) (apparent Kd ~ 0.

Functional analysis of SERCA1b, a highly expressed SERCA1 variant in myotonic dystrophy type 1 muscle.

Myotonic dystrophy type 1 (DM1) is a genetic disorder in which multiple genes are aberrantly spliced. Sarco/endoplasmic reticulum Ca(2+)-ATPase 1 (SERCA1) is one of these genes, and it encodes a P-type ATPase. SERCA1 transports Ca(2+) from the cytosol to the lumen, and is involved in muscular relaxation.

Escherichia coli pyruvate:flavodoxin oxidoreductase, YdbK - regulation of expression and biological roles in protection against oxidative stress.

E. coli YdbK is predicted to be a pyruvate:flavodoxin oxidoreductase (PFOR). However, enzymatic activity and the regulation of gene expression of it are not well understood.

Structural and functional properties of CiNTH, an endonuclease III homologue of the ascidian Ciona intestinalis: critical role of N-terminal region.

Oxidatively damaged bases in DNA can cause cell death, mutation and/or cancer induction. To overcome such deleterious effects of DNA base oxidation, cells are equipped with base excision repair (BER) initiated by DNA glycosylases. Endonuclease III (Nth), a major DNA glycosylase, mainly excises oxidatively damaged pyrimidines from DNA.

Mitochondria-targeted superoxide dismutase (SOD2) regulates radiation resistance and radiation stress response in HeLa cells.

Reactive oxygen species (ROS) act as a mediator of ionizing radiation-induced cellular damage. Previous studies have indicated that MnSOD (SOD2) plays a critical role in protection against ionizing radiation in mammalian cells. In this study, we constructed two types of stable HeLa cell lines overexpressing SOD2, HeLa S3/SOD2 and T-REx HeLa/SOD2, to elucidate the mechanisms underlying the protection against radiation by SOD2.

NDX-1 protein hydrolyzes 8-oxo-7, 8-dihydrodeoxyguanosine-5'-diphosphate to sanitize oxidized nucleotides and prevent oxidative stress in Caenorhabditis elegans.

8-oxo-dGTP is generated in the nucleotide pool by direct oxidation of dGTP or phosphorylation of 8-oxo-dGDP. It can be incorporated into DNA during replication, which would result in mutagenic consequences. The frequency of spontaneous mutations remains low in cells owing to the action of enzymes degrading such mutagenic substrates.

Trinitrophenyl derivatives bind differently from parent adenine nucleotides to Ca2+-ATPase in the absence of Ca2+.

Trinitrophenyl derivatives of adenine nucleotides are widely used for probing ATP-binding sites. Here we describe crystal structures of Ca(2+)-ATPase, a representative P-type ATPase, in the absence of Ca(2+) with bound ATP, trinitrophenyl-ATP, -ADP, and -AMP at better than 2.4-Å resolution, stabilized with thapsigargin, a potent inhibitor.

CiMutT, an asidian MutT homologue, has a 7, 8-dihydro-8-oxo-dGTP pyrophosphohydrolase activity responsible for sanitization of oxidized nucleotides in Ciona intestinalis.

The oxidized nucleotide precursors 7, 8-dihydro-8-oxo-dGTP (8-oxo-dGTP) and 1, 2-dihydro-2-oxo-dATP (2-oxo-dATP) are readily incorporated into nascent DNA strands during replication, which would cause base substitution mutations. E. coli MutT and human homologue hMTH1 hydrolyze 8-oxo-dGTP, thereby preventing mutations.

Error-Prone Translesion DNA Synthesis by Escherichia coli DNA Polymerase IV (DinB) on Templates Containing 1,2-dihydro-2-oxoadenine.

Escherichia coli DNA polymerase IV (Pol IV) is involved in bypass replication of damaged bases in DNA. Reactive oxygen species (ROS) are generated continuously during normal metabolism and as a result of exogenous stress such as ionizing radiation. ROS induce various kinds of base damage in DNA.

Purification and characterization of Caenorhabditis elegans NTH, a homolog of human endonuclease III: essential role of N-terminal region.

Oxidatively damaged bases in DNA cause many types of deleterious effects. The main enzyme that removes such lesions is DNA glycosylase, and accordingly, DNA glycosylase plays an important role in genome stability. Recently, a relationship between DNA glycosylases and aging has been suggested, but it remains controversial.

KsgA, a 16S rRNA adenine methyltransferase, has a novel DNA glycosylase/AP lyase activity to prevent mutations in Escherichia coli.

The 5-formyluracil (5-foU), a major mutagenic oxidative damage of thymine, is removed from DNA by Nth, Nei and MutM in Escherichia coli. However, DNA polymerases can also replicate past the 5-foU by incorporating C and G opposite the lesion, although the mechanism of correction of the incorporated bases is still unknown. In this study, using a borohydride-trapping assay, we identified a protein trapped by a 5-foU/C-containing oligonucleotide in an extract from E.

Generation, biological consequences and repair mechanisms of cytosine deamination in DNA.

Base moieties in DNA are spontaneously threatened by naturally occurring chemical reactions such as deamination, hydrolysis and oxidation. These DNA modifications have been considered to be major causes of cell death, mutations and cancer induction in organisms. Organisms have developed the DNA base excision repair pathway as a defense mechanism to protect them from these threats.

Cloning and characterization of uracil-DNA glycosylase and the biological consequences of the loss of its function in the nematode Caenorhabditis elegans.

Uracil arises in DNA from spontaneous deamination of cytosine and through incorporation of dUMP by DNA polymerase during DNA replication. Excision of uracil by the action of uracil-DNA glycosylase (Ung) initiates the base excision repair pathway to counter the promutagenic base modification. In this study, we cloned a cDNA-encoding Caenorhabditis elegans homologue (CeUng-1) of Escherichia coli Ung.

Recombinant Schizosaccharomyces pombe Nth1 protein exhibits DNA glycosylase activities for 8-oxo-7,8-dihydroguanine and thymine residues oxidized in the methyl group.

Bacteria and eukaryotes possess redundant enzymes that recognize and remove oxidatively damaged bases from DNA through base excision repair. DNA glycosylases remove damaged bases to initiate the base excision repair. The exocyclic methyl group of thymine does not escape oxidative damage to produce 5-formyluracil (5-foU) and 5-hydroxymethyluracil (5-hmU).

The Shizosaccharomyces pombe homolog (SpMYH) of the Escherichia coli MutY is required for removal of guanine from 8-oxoguanine/guanine mispairs to prevent G:C to C:G transversions.

The frequency of G:C-->C:G transversions significantly increases upon exposure of cells to ionizing radiation or reactive oxygen species. Transversions can be prevented by base excision repair, which removes the causative modified bases from DNA. Our previous studies revealed that MutY is responsible for removing guanine from 7,8-dihydro-8-oxoguanine/guanine mispairs (8-oxoG/G) and prevents the generation of G:C-->C:G transversions in E.

DNA glycosylase activities for thymine residues oxidized in the methyl group are functions of the hNEIL1 and hNTH1 enzymes in human cells.

Bacteria and eukaryotes possess redundant activities that recognize and remove oxidatively damaged bases from DNA through base excision repair. DNA glycosylases excise damaged bases to initiate the base excision repair pathway. hOgg1 and hNTH1, homologues of E.