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)

High levels of expression of cloned genes have been obtained in mammalian cells by using poxvirus-derived insertion/expression vectors. These vectors employ the cis-acting element (CAE I) that directs the transcription of one of the most strongly expressed genes of cowpox virus. This gene (the 160K gene) encodes the 160-kDa protein that is the major component of the A-type cytoplasmic inclusions. Its counterpart in vaccinia virus (VV) is the 94K gene contained in the HindIII A fragment of the viral DNA. Two insertion vectors have been constructed; each is designed to allow cloned genes to be placed immediately downstream of a modified version of CAE I within a poxvirus genome. One vector, p1200, enables the CAE I-cloned-gene constructs to be inserted into the thymidine kinase gene of VV. This vector was used to create a VV recombinant that directed expression of the chloramphenicol acetyltransferase (CAT) gene. The other vector, p2101, enables the CAE I-cloned-gene constructs to be inserted into the VV 94K gene. The prototype of this vector was used to create a VV recombinant that directed expression of a hybrid CAT-lacZ gene. Infection of cultured human cells with these recombinants led to high levels of synthesis of either the CAT gene product or the CAT-lacZ gene product. Each of these proteins was produced in quantities that were easily detected by Coomassie blue staining of total cell proteins resolved by polyacrylamide gel electrophoresis. We estimate that these vectors are capable of directing the synthesis of milligram amounts of gene product per 10(9) mammalian cells.
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PMID:A poxvirus-derived vector that directs high levels of expression of cloned genes in mammalian cells. 284 5

Caprine arthritis-encephalitis virus (CAEV) and visna virus are pathogenic lentiviruses of goats and sheep which share morphologic features and sequence homology with human T-cell lymphotropic virus type III (HTLV-III), the etiologic agent of the acquired immune deficiency syndrome. The nucleotide sequence of the CAEV long terminal repeat (LTR) was determined, and it was found to be 450 base pairs long, with U3, R, and U5 regions of 287, 85, and 78 base pairs, respectively. Portions of the CAEV LTR are closely homologous to analogous regions of visna virus. The CAEV LTR is not significantly homologous with the HTLV-III LTR; however, like HTLV-III, visna virus, and equine infectious anemia virus, CAEV uses tRNA lysine as a primer for reverse transcription. The transcriptional activity of the CAEV and visna virus LTRs was measured by a chloramphenicol acetyltransferase assay, and the activity of the visna virus LTR was generally higher in a variety of uninfected cell types. Infection of cells with visna virus markedly increased gene expression directed by either the CAEV or visna virus LTR, but in contrast, infection of cells with CAEV had little effect on the activity of either LTR. The lack of trans-activation by CAEV, a virus which causes debilitating arthritis and encephalitis in goats, suggests that trans-activation may not be a general property of pathogenic lentiviruses.
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PMID:Nucleotide sequence and transcriptional activity of the caprine arthritis-encephalitis virus long terminal repeat. 302 73

Caprine arthritis-encephalitis virus (CAEV) is a lentivirus which is closely related by nucleotide sequence and biological properties to visna virus. Sequence analysis of the CAEV genome revealed the presence of a small open reading frame (ORF) which shares amino acid identity with the visna virus tat gene. Using an infectious molecular clone of CAEV the role of the tat ORF in viral replication was examined. Mutations were made in the tat ORF that introduced two in frame stop codons six amino acids downstream of the tat AUG; in addition, a deletion mutant was made that removed most of the tat ORF. Both of these mutants had greatly reduced virus titers (> 1000-fold less than the wild type infectious clone). Co-transfection of a tat expressing plasmid with these viruses containing the tat ORF mutations resulted in higher levels of virus production demonstrating that the effects of both mutants are tat specific. These mutants provide data that the CAEV tat gene is necessary for efficient virus replication. Analysis of the RNA in these transfected cells showed that complementation of the tat gene was in trans and not the result of recombination. Analysis of the gag and rev proteins in the transfected cells demonstrated that these proteins were not detectable in cells transfected with the tat mutants but could be readily detected when the mutations were complemented in trans with a tat expression vector. To test for tat mediated trans-activation a plasmid expressing the CAEV tat ORF was co-transfected with plasmids containing either the CAEV or visna virus LTR driving transcription of the bacterial chloramphenicol acetyltransferase gene (CAT). These experiments indicate that one function of the CAEV tat protein is to trans-activate gene expression from the viral promoter. RNase protection analysis of CAT mRNA from co-transfected cells demonstrated that CAEV Tat trans-activates gene expression by increasing steady-state levels of mRNA.
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PMID:The CAEV tat gene trans-activates the viral LTR and is necessary for efficient viral replication. 821 71