Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.48 (transcriptase)
 9,479 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

8-Hydroxyguanine (oh(8)G) is a major form of oxidative DNA damage produced by reactive oxygen species (ROS). The human OGG1 gene encodes a DNA glycosylase that excises oh(8)G from double-stranded DNA. In this study, we investigated a mode of interaction between OGG1 and APEX proteins in the repair of oh(8)G under oxidative stresses. DNA cleavage assay using oh(8)G-containing oligonucleotides showed that the phosphodiester bond on the 3'-side of oh(8)G was cleaved by the AP lyase activity of GST-OGG1 protein and the phosphodiester bond on the 5'-side of oh(8)G was cleaved by the DNA 3'-repair diesterase activity of APEX protein. Gel mobility shift assay showed that the complex of GST-OGG1 protein and oh(8)G-containing oligonucleotides mostly changed into the complex of APEX protein and oligonucleotides by addition of APEX protein into the reaction mixture. We next analyzed alterations in the amount of 8-hydroxydeoxyguanosine (oh(8)dG) in DNA and the levels of OGG1 and APEX expression in HeLa S3 cells treated with 2mM hypochlorous acid, a kind of ROS. An approximately four-fold increase in the amount of oh(8)G was detected by the HPLC-ECD method. Reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blot analyses indicated that the level of APEX expression increased approximately four-fold, whereas the level of OGG1 expression was unchanged. However, in the DNA cleavage assay, the AP lyase activity of GST-OGG1 protein was significantly increased in the presence of a molar excess of APEX protein. These results indicate that, under severe oxidative stresses, OGG1 mRNA is not induced and the amount of OGG1 protein is not remarkably increased, but the activity of OGG1 protein is enhanced by the increase of APEX protein in the cells.
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PMID:Enhancement of OGG1 protein AP lyase activity by increase of APEX protein. 1135 34

Streptomyces coelicolor A3(2) is a rubber-degrading actinomycete that harbors one gene coding for a latex clearing protein (lcpA3(2)). Within the genome of S. coelicolor A3(2), we identified a gene coding for a novel protein of the TetR family (LcpRBA3(2)) downstream of lcpA3(2) and demonstrated its binding upstream of lcpA3(2). This indicates a role of LcpRBA3(2) in the regulation of lcp expression. LcpRBA3(2) shows no homology to LcpRVH2, a putative regulator of lcp expression in Gordonia polyisoprenivorans VH2. Additionally, LcpRVH2 homologs did not occur in the genome of S. coelicolor A3(2). Reverse transcriptase (RT) experiments showed that the expression of lcpA3(2) and lcpRBA3(2) is induced with poly(cis-1,4-isoprene) as sole carbon source. For further experiments, we heterologously expressed lcpRBA3(2) in Escherichia coli, purified the protein, and subsequently verified a binding of LcpRBA3(2) upstream of lcpA3(2). The operator site was examined by a DNase I footprinting assay: it comprises 31 bp and exhibits an inverted repeat of nine bases for the putative binding region. Interestingly, two N-terminal DNA-binding HTH domains of the TetR-type (PF00440) were identified within the sequence of LcpRBA3(2). The native molecular weight of LcpRBA3(2) was determined as 44 kDa by size exclusion chromatography which correlates to the molecular weight of a monomer. Normally, proteins of the TetR family occur as dimers so that the monomeric state is a novelty. Furthermore, LcpRBA3(2) homologs were identified in silico in several Lcp-containing actinomycetes, suspecting a conserved regulation mechanism. Apparently, the expression of lcps is regulated either by an LcpRB or by an LcpR.
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PMID:Identification of LcpRBA3(2), a novel regulator of lcp expression in Streptomyces coelicolor A3(2). 3111 50