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showing 10 items of 730 documents
Interaction of Mitogen-activated Protein Kinases with the Kinase Interaction Motif of the Tyrosine Phosphatase PTP-SL Provides Substrate Specificity …
1999
ERK1 and ERK2 associate with the tyrosine phosphatase PTP-SL through a kinase interaction motif (KIM) located in the juxtamembrane region of PTP-SL. A glutathione S-transferase (GST)-PTP-SL fusion protein containing the KIM associated with ERK1 and ERK2 as well as with p38/HOG, but not with the related JNK1 kinase or with protein kinase A or C. Accordingly, ERK2 showed in vitro substrate specificity to phosphorylate GST-PTP-SL in comparison with GST-c-Jun. Furthermore, tyrosine dephosphorylation of ERK2 by the PTP-SLDeltaKIM mutant was impaired. The in vitro association of ERK1/2 with GST-PTP-SL was highly stable; however, low concentrations of nucleotides partially dissociated the ERK1/2.P…
A novel regulatory mechanism of MAP kinases activation and nuclear translocation mediated by PKA and the PTP-SL tyrosine phosphatase
1999
Protein tyrosine phosphatase PTP-SL retains mitogen-activated protein (MAP) kinases in the cytoplasm in an inactive form by association through a kinase interaction motif (KIM) and tyrosine dephosphorylation. The related tyrosine phosphatases PTP-SL and STEP were phosphorylated by the cAMP-dependent protein kinase A (PKA). The PKA phosphorylation site on PTP-SL was identified as the Ser231 residue, located within the KIM. Upon phosphorylation of Ser231, PTP-SL binding and tyrosine dephosphorylation of the MAP kinases extracellular signal–regulated kinase (ERK)1/2 and p38α were impaired. Furthermore, treatment of COS-7 cells with PKA activators, or overexpression of the Cα catalytic subunit …
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…
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…
APE/Ref-1 and the mammalian response to genotoxic stress.
2003
Human apurinic/apyrimidinic endonuclease/redox factor-1 (hAPE/Ref-1) is a multifunctional protein involved in the repair of DNA damaged by oxidative or alkylating compounds as well as in the regulation of stress inducible transcription factors such as AP-1, NF-kappaB, HIF-1 and p53. With respect to transcriptional regulation, both redox dependent and independent mechanisms have been described. APE/Ref-1 also acts as a transcriptional repressor. Recent data indicate that APE/Ref-1 negatively regulates the activity of the Ras-related GTPase Rac1. How these different physiological activities of APE/Ref-1 are coordinated is poorly understood. So far, convincing evidence is available that the ex…
Cockayne syndrome: varied requirement of transcription-coupled nucleotide excision repair for the removal of three structurally different adducts fro…
2014
Hereditary defects in the transcription-coupled nucleotide excision repair (TC-NER) pathway of damaged DNA cause severe neurodegenerative disease Cockayne syndrome (CS), however the origin and chemical nature of the underlying DNA damage had remained unknown. To find out, to which degree the structural properties of DNA lesions determine the extent of transcription arrest in human CS cells, we performed quantitative host cell reactivation analyses of expression vectors containing various synthetic adducts. We found that a single 3-(deoxyguanosin-N 2-yl)-2-acetylaminofluorene adduct (dG(N 2)-AAF) constitutes an unsurmountable obstacle to transcription in both CS-A and CS-B cells and is remov…
Late activation of stress kinases (SAPK/JNK) by genotoxins requires the DNA repair proteins DNA-PKcs and CSB.
2005
Although genotoxic agents are powerful inducers of stress kinases (SAPK/JNK), the contribution of DNA damage itself to this response is unknown. Therefore, SAPK/JNK activation of cells harboring specific defects in DNA damage-recognition mechanisms was studied. Dual phosphorylation of SAPK/JNK by the genotoxin methyl methanesulfonate (MMS) occurred in two waves. The early response (≤2 h after exposure) was similar in cells knockout for ATM, PARP, p53, and CSB or defective in DNA-PKcscompared with wild-type cells. The late response however (≥4 h), was drastically reduced in DNA-PKcsand Cockayne's syndrome B (CSB)-deficient cells. Similar results were obtained with human cells lacking DNA-PKc…
Purification of Leuconostoc mesenteroides citrate lyase and cloning and characterization of the citCDEFG gene cluster
1998
ABSTRACT A citrate lyase (EC 4.1.3.6 ) was purified 25-fold from Leuconostoc mesenteroides and was shown to contain three subunits. The first 42 amino acids of the β subunit were identified, as well as an internal peptide sequence spanning some 20 amino acids into the α subunit. Using degenerated primers from these sequences, we amplified a 1.2-kb DNA fragment by PCR from Leuconostoc mesenteroides subsp. cremoris . This fragment was used as a probe for screening a Leuconostoc genomic bank to identify the structural genes. The 2.7-kb gene cluster encoding citrate lyase of L. mesenteroides is organized in three open reading frames, citD , citE , and citF , encoding, respectively, the three ci…
Effect of natamycin on the enumeration, genetic structure and composition of bacterial community isolated from soils and soybean rhizosphere
2004
Natamycin is commonly used to control fungal growth on agar media used for bacterial enumeration or strain isolation. However, there is no conclusive report on the possible effect of this antibiotic on bacterial growth or on the diversity of the recovered soil bacteria. Therefore, the possible effects of natamycin on the numbers of bacteria isolated at 12 degrees C from three different soils and soybean rhizosphere soil were investigated using natamycin concentrations ranging from 0 to 200 mg l(-1). Our results demonstrate that natamycin concentrations, which inhibit the growth of fungi on the media, have a small but significant inhibitory effect on the number of bacterial colony forming un…
Identification of a third secondary carrier (DcuC) for anaerobic C4-dicarboxylate transport in Escherichia coli: roles of the three Dcu carriers in u…
1996
In Escherichia coli, two carriers (DcuA and DcuB) for the transport of C4 dicarboxylates in anaerobic growth were known. Here a novel gene dcuC was identified encoding a secondary carrier (DcuC) for C4 dicarboxylates which is functional in anaerobic growth. The dcuC gene is located at min 14.1 of the E. coli map in the counterclockwise orientation. The dcuC gene combines two open reading frames found in other strains of E. coli K-12. The gene product (DcuC) is responsible for the transport of C4 dicarboxylates in DcuA-DcuB-deficient cells. The triple mutant (dcuA dcuB dcuC) is completely devoid of C4-dicarboxylate transport (exchange and uptake) during anaerobic growth, and the bacteria are…