Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.3.1.28 (chloramphenicol acetyltransferase)
 5,100 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Promiscuous transcriptional activity of the reticuloendotheliosis virus (REV) long terminal repeat (LTR) was detected in transient expression assays using LTR-chloramphenicol acetyltransferase-encoding gene chimeras, and cells of diverse species and tissue type; levels of expression from two different REV LTRs correlate with reports of pathogenicity of the respective viruses in vivo. REVs do not encode a transactivator targeted to the viral LTR, and cells infected with Marek's disease virus, a herpesvirus with an overlapping host range, do not express factors that preferentially enhance expression from REV or avian sarcoma/leukemia virus LTRs. REV LTRs work efficiently in human lymphoid cells, and are viable alternatives to promoters commonly used for expression of cloned genes. They may also prove useful in the identification of new, ubiquitous cellular transcription factors.
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PMID:Reticuloendotheliosis virus long terminal repeat elements are efficient promoters in cells of various species and tissue origin, including human lymphoid cells. 133 12

Interactions between factors in duck and chick embryo fibroblast (DEF and CEF, respectively) nuclear extracts and the Marek's disease virus (MDV) gp57-65 gene promoter were investigated. Results of in vitro transcription and gel mobility-shift assays indicated that multiple cellular factors interact with 5'-flanking sequences of the MDV gp57-65 gene. One sequence-specific DNA binding activity (termed ACF for avian cell factor(s)) was identified by interaction of DEF and CEF nuclear extract proteins with a particular site (nucleotides -193 to -177) in the MDV gp57-65 gene promoter. Binding of ACF to its apparent recognition sequence, contained within the 17-bp oligonucleotide 5'-CTAGTTTACTTGTTTGT-3' (ACF-12), was highly sequence-specific. Radiolabeled ACF-12 oligonucleotide bound significant ACF protein in the presence of a 400-fold molar excess of unlabeled nonspecific competitor DNA. A similar amount of specific competitor completely abolished ACF binding to probe DNA. Deletion of the ACF binding site from MDV gp57-65 gene promoters linked to a chloramphenicol acetyltransferase (CAT) reporter gene reduced expression of CAT activity by twofold relative to that seen with a gp57-65 promoter-CAT construct containing an intact ACF binding site. Transfection inhibition assays using double-stranded ACF binding site competitors reduced steady-state levels of gp57-65 mRNA in MDV infected cells by over twofold relative to those in control infected cells. Introduction of a similar amount of nonspecific double-stranded oligonucleotide had no adverse effect on gp57-65 mRNA levels. These data suggest that ACF is important for efficient expression of gp57-65.
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PMID:Identification of a novel transcription factor, ACF, in cultured avian fibroblast cells that interacts with a Marek's disease virus late gene promoter. 165 7

Marek's disease virus (MDV) is an avian herpesvirus that induces a variety of diseases, including T-cell lymphomas, in chickens. In latently infected, transformed lymphoid cells, very few viral transcripts or proteins are detected. We previously described a gene, meq (MDV EcoQ), which is persistently expressed in MDV-transformed tumor samples and cell lines. meq codes for a 339-amino-acid protein with a basic-leucine zipper domain near its N terminus and a proline-rich domain near its C terminus. The basic-leucine zipper domain shows homology with Jun/Fos family proteins, whereas the proline-rich domain resembles that of the WT-1 tumor suppressor protein. These structural features raise the possibility that Meq functions as a transcription factor in regulating viral latency or oncogenesis. In this report, we show that the proline-rich domain is a potent transcription activator when fused to the yeast (Saccharomyces cerevisiae) Gal4(1-147) DNA-binding domain. The transactivation activity maps to the C-terminal 130 amino acids, with the last 33 amino acids essential. In the absence of these 33 amino acids, a two-and-one-half proline-rich repeat structure was found to exhibit repression activity. We further show that Meq is able to dimerize not only with itself but also with c-Jun. Meq/c-Jun heterodimers bind to an AP1-like sequence in the meq promoter region with an affinity much greater than that of Meq/Meq or c-Jun/c-Jun homodimers. Cotransfection chloramphenicol acetyltransferase assays suggest that the Meq/c-Jun heterodimers can up-regulate Meq expression in both chicken embryo fibroblasts and F9 cells. Our data provide the first biochemical evidence that Meq is a transcriptional factor and identify c-Jun as one of Meq's interacting partners.
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PMID:Transactivation activity of Meq, a Marek's disease herpesvirus bZIP protein persistently expressed in latently infected transformed T cells. 776 61

Marek's disease virus (MDV) contains a bi-directional promoters located between pp38 gene and 1.8-kb mRNA in the long inverted repeat region of the viral genome. The involvement of pp38 gene in up-regulating the activity of these promoters was analyzed by transient expression of chloramphenicol acetyltransferase (CAT) reporter gene. Two CAT reporter plasmids, pP(pp38)-CAT and pP(1.8-kb)-CAT, were constructed to express CAT under the control of the bi-directional promoter in both orientations. These plasmids were transfected into chicken embryonic fibroblast (CEF), infected with rMd5 and pp38 deleted rMd5 (rMd5/Deltapp38), respectively. No CAT activity was detected in uninfected CEF as expected. CAT activities in rMd5/Deltapp38 virus infected CEF (rMd5/Deltapp38-CEF) were 3.5-fold lower using pP(pp38)-CAT and 12-fold lower using pP(1.8-kb)-CAT than those of the parental rMd5 infected CEF (rMd5-CEF). The significantly lower promoter activity in the pp38 deletion virus suggests that pp38 can regulate the activity of the bi-directional promoters, especially in the direction of 1.8-kb mRNA family. Co-transfection of pp38-expressing plasmid (pcDNA-pp38) into rMd5/Deltapp38-CEF significantly increased the activity of the bi-directional promoters using either pP(pp38)-CAT or pP(1.8-kb)-CAT. DNA mobility shift assay showed a binding of the 73-bp sequence of the bi-directional promoter with rMd5-CEF but not with rMd5/Deltapp38-CEF or uninfected CEF lysates. However, rMd5/Deltapp38-CEF lysates could bind the same 73-bp promoter sequence when co-transfected with pp38-expressing plasmid (pcDNA-pp38). All these data taken together suggest pp38 plays an important role in regulating the transcriptional activity of the bi-directional promoter.
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PMID:The role of pp38 in regulation of Marek's disease virus bi-directional promoter between pp38 and 1.8-kb mRNA. 1660 52