Search results for "binding"
showing 10 items of 3896 documents
d-Alanyl-d-Alanine Carboxypeptidase in the Bacterial Form and L-Form of Proteus mirabilis
1975
Membranes of the bacterial form and the stable and unstable L-forms of Proteus mirabilis contain LD and DD-carboxypeptidase. The DD-carboxypeptidase is inhibited non-competitively by penicillin G. The enzyme of the bacterial form is highly penicillin-sensitive (Ki - 4 X 10(-9) M penicillin G). Inhibition is only partly reversible by treatment with penicillinase or by dialysis against buffer. In contrast, the DD-carboxypeptidase of the unstable L-form, grown in the presence of penicillin, is 175-fold less penicillin-sensitive (Ki = 7 X 10(7) M penicillin G). Inhibition is completely reversed by penicillinase or dialysis. After inhibition by penicillin and subsequent reactivation the penicill…
Cascade complex formation by phosphate in the cobalt(II)/[30]aneN10 anaerobic system
1993
Abstract The interaction of phosphate with the mono- and binuclear cobalt(II) complexes of [30]aneN 10 (1,4,7,10,13,16,19,22,25,28-decaazacyclotriacontane) has been studied by potentiometry in 0.15 mol dm −3 NaClO 4 solution at 298.15 K under anaerobic conditions. The stable species [CoH 2 ([30]aneN 10 )PO 4 ] + , [CoH 4 ([30]aneN 10 )PO 4 ] 3+ , [Co 2 H([30]aneN 10 )PO 4 ] 2+ , [Co 2 H 2 ([30]aneN 10 )PO 4 ] 3+ and [Co 2 H 3 ([30]aneN 10 )PO 4 ] 4+ , where the phosphate anion is directly bound to the metal ions or acts as a second sphere ligand, are formed and their stability constants have been determined. The results obtained allowed for the selection of suitable conditions for the study…
Sex-specific windows for high mRNA expression of DNA methyltransferases 1 and 3A and methyl-CpG-binding domain proteins 2 and 4 in human fetal gonads
2006
DNA methyltransferases (DNMTs) and 5-methyl-CpG-binding domain proteins (MBDs) are involved in the acquisition of parent-specific epigenetic modifications in human male and female germ cells. Reverse Northern blot analyses demonstrated sex-specific differences in mRNA expression for the maintenance DNMT1 and the de novo DNMT3A in developing testis and ovary. In fetal testis DNMT1 and DNMT3A expression peaked in mitotically arrested spermatogonia around 21 weeks gestation. In fetal ovary transcriptional upregulation of DNMT1 and DNMT3A occurred during a very brief period at 16 weeks gestation, when the oocytes proceeded through meiotic prophase. Fetal gonads showed several fold higher DNMT3A…
Compromised repair of radiation-induced DNA double-strand breaks in Fanconi anemia fibroblasts in G2
2020
Fanconi anemia (FA) is a rare chromosomal instability syndrome with various clinical features and high cancer incidence. Despite being a DNA repair disorder syndrome and a frequently observed clinical hypersensitivity of FA patients towards ionizing radiation, the experimental evidence regarding the efficiency of radiation-induced DNA double-strand break (DSB) repair in FA is very controversial. Here, we performed a thorough analysis of the repair of radiation-induced DSBs in G1 and G2 in FA fibroblasts of complementation groups A, C, D1 (BRCA2), D2, E, F, G and P (SLX4) in comparison to normal human lung and skin fibroblasts. γH2AX, 53BP1, or RPA foci quantification after X-irradiation was…
Deinococcus radiodurans' SRA-HNH domain containing protein Shp (Dr1533) is involved in faithful genome inheritance maintenance following DNA damage
2018
WOS:000452343100012; International audience; Background: Deinococcus radiodurans R1 (DR) survives conditions of extreme desiccation, irradiation and exposure to genotoxic chemicals, due to efficient DNA breaks repair, also through Mn2+ protection of DNA repair enzymes. Methods: Possible annotated domains of the DR1533 locus protein (Shp) were searched by bioinformatic analysis. The gene was cloned and expressed as fusion protein. Band-shift assays of Shp or the SRA and HNH domains were performed on oligonucleotides, genomic DNA from E. coif and DR. slip knock-out mutant was generated by homologous recombination with a kanamycin resistance cassette. Results: DR1533 contains an N-terminal SRA…
Molecular modes of action of cantharidin in tumor cells
2005
Cancer chemotherapy is often limited by patient's toxicity and tumor drug resistance indicating that new drug development and modification of existing drugs is critical for improving the therapeutic response. Traditional Chinese medicine is a rich source of potential anticancer agents. In particular, cantharidin (CAN), the active principle ingredient from the blister beetle, Mylabris, has anti-tumor activity, but the cytotoxic mechanism is unknown. In leukemia cells, cantharidin induces apoptosis by a p53-dependent mechanism. Cantharidin causes both DNA single- and double-strand breaks. Colony-forming assays with knockout and transfectant cells lines showed that DNA polymerase beta, but not…
Poly(ADP-ribosyl)ation accelerates DNA repair in a pathway dependent on Cockayne syndrome B protein
2003
Activation of poly(ADP-ribose)polymerases 1 and 2 (PARP-1 and PARP-2) is one of the earliest responses of mammalian cells to DNA damage by numerous genotoxic agents. We have analysed the influence of PARP inhibition, either achieved by over-expression of the DNA binding domain of PARP-1 or by treatment with 3,4-dihydro-5-[4-(1-piperidinyl)butoxyl]-1(2H)-isoquinolinone, on the repair of single-strand breaks (SSB), pyrimidine dimers and oxidative base modifications sensitive to Fpg protein (mostly 8-hydroxyguanine) in mammalian cells at very low, non-cytotoxic levels of DNA damage. The data show that the repair rates of all three types of DNA damage are significantly lower in PARP-inhibited c…
Interaction with OGG1 Is Required for Efficient Recruitment of XRCC1 to Base Excision Repair and Maintenance of Genetic Stability after Exposure to O…
2015
International audience; XRCC1 is an essential protein required for the maintenance of genomic stability through its implication in DNA repair. The main function of XRCC1 is associated with its role in the single-strand break (SSB) and base excision repair (BER) pathways that share several enzymatic steps. We show here that the polymorphic XRCC1 variant R194W presents a defect in its interaction with the DNA glycosylase OGG1 after oxidative stress. While proficient for single-strand break repair (SSBR), this variant does not colocalize with OGG1, reflecting a defect in its involvement in BER. Consistent with a role of XRCC1 in the coordination of the BER pathway, induction of oxidative base …
Oxidative stress triggers the preferential assembly of base excision repair complexes on open chromatin regions
2010
How DNA repair machineries detect and access, within the context of chromatin, lesions inducing little or no distortion of the DNA structure is a poorly understood process. Removal of oxidized bases is initiated by a DNA glycosylase that recognises and excises the damaged base, initiating the base excision repair (BER) pathway. We show that upon induction of 8-oxoguanine, a mutagenic product of guanine oxidation, the mammalian 8-oxoguanine DNA glycosylase OGG1 is recruited together with other proteins involved in BER to euchromatin regions rich in RNA and RNA polymerase II and completely excluded from heterochromatin. The underlying mechanism does not require direct interaction of the prote…
Nucleotide excision repair of abasic DNA lesions
2019
AbstractApurinic/apyrimidinic (AP) sites are a class of highly mutagenic and toxic DNA lesions arising in the genome from a number of exogenous and endogenous sources. Repair of AP lesions takes place predominantly by the base excision pathway (BER). However, among chemically heterogeneous AP lesions formed in DNA, some are resistant to the endonuclease APE1 and thus refractory to BER. Here, we employed two types of reporter constructs accommodating synthetic APE1-resistant AP lesions to investigate the auxiliary repair mechanisms in human cells. By combined analyses of recovery of the transcription rate and suppression of transcriptional mutagenesis at specifically positioned AP lesions, w…