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)

The Escherichia coli argU gene encodes the rare arginine tRNA, tRNA(UCUArg), which decodes the similarly rare AGA codons. The argU promoter is, with two exceptions, a typical, strongly expressed stable RNA gene promoter which is stimulated by an upstream activator sequence. Unlike other tRNA operons, however, argU expression is severely inhibited by sequences downstream of the transcription start point. In vivo, nucleotides +2 to +45 inhibited expression by 25- to 100-fold when measured by fusion of argU promoter regions to the chloramphenicol acetyltransferase reporter gene or by quantitative primer extension analysis. In vitro, linearized argU promoter fragments on which the argU region ended at +1 supported 5- to 10-fold-more transcription than when the argU region ended at +45. This difference in degree of inhibition between in vivo and in vitro conditions suggests that several factors, some of which could be absent in vitro, might limit expression in vivo. Alternatively, one mechanism might limit expression both in vivo and in vitro but function more efficiently in vivo. A second difference from strongly expressed stable RNA promoters is the fact the argU gene is relatively insensitive to growth rate regulation, at least when assayed on a multicopy plasmid.
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PMID:Expression of argU, the Escherichia coli gene coding for a rare arginine tRNA. 154 36

The AGG and AGA are the least used arginine codons in E. coli but they are the most preferable ones in eukaryotes. The low expression of some eucaryotic genes (such as human alpha-1 interferon gene) which contain clusters of AGG codons is explained either by the limited pool of the tRNA(AGG) (Varenne and Lazdunski, 1986) or by the competition of these clusters with the Shine-Dalgarno (SD) sequence (Ivanov et al., 1992). The aim of the present study is to demonstrate the in vivo capacity of AGG tandems to bind to bacterial ribosomes. The two tandems of AGG codons (Arg12 Arg13 and Arg163 Arg164) of hIF alpha 1 with their surrounding nucleotides were cloned in a bacterial expression plasmid containing a strong promoter and a reporter gene (chloramphenicol acetyltransferase, CAT) devoid of a ribosome binding site. The results obtained showed that both AGG tandems initiated translation of the CAT mRNA with an efficiency equal to that of the consensus SD sequence and several fold higher than the native SD sequence of the CAT gene.
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PMID:Domains in human interferon alpha-1 gene containing tandems of arginine codons AGG play the role of translational initiators in E. coli. 764 Oct 76

Recently, we have established nine nasopharyngeal carcinoma (NPC) cell lines in which only one cell line showed the p53 mutation. For investigation of the p53 mutation in this line, immunostaining using anti-p53 antibody was applied and showed the presence of p53 protein in the cytoplasm but not in the nucleus. Single strand conformation polymorphism analysis of the p53 gene showed one normal and one additional DNA band. Cloning and sequencing of PCR-amplified DNA showed an AGA (arginine) to ACA (threonine) heterozygous point mutation at codon 280. Transfection of the p53 DNA binding sequence and chloramphenicol acetyltransferase assay revealed loss of transcriptional activation function of endogenous p53 protein. Co-localization of the endogenous and the transfected exogenous p53 protein by polyclonal antibodies to anti-p53 protein revealed strong exogenous p53 staining in the transfected nuclei and weak staining of endogenous p53 protein in the cytoplasm. We concluded that (a) a heterozygous point mutation at codon 280 was identified in the NPC-TW 06 cell line; (b) the point mutation may cause the stagnation of mutant p53 protein in the cytoplasm, and loss of its transcriptional activation function; (c) endogenous and exogenous p53 protein can be co-localized at the same time in the transfected cells; and (d) 280 mutant p53 protein in NPC cells does not cause a decrease or increase in sensitivity to chemotherapy.
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PMID:Co-localization of endogenous and exogenous p53 proteins in nasopharyngeal carcinoma cells. 921 25

In Escherichia coli mRNA, the arginine codons AGA/AGG and the isoleucine codon AUA are rarely used with frequencies of about 0.35% and 0.41%, respectively. Six genes with a different number of these codons were expressed in an E. coli in vitro coupled transcription/translation system, which contained either tRNA prepared from E. coli cells carrying a plasmid with argU and ileX genes encoding rare tRNAs (tRNA(arg)(AGA/AGG) and tRNA(ile)(AUA)), designated codon-plus tRNA, or normal tRNA from cells lacking the plasmid. Genes having a low number of the rare codons, such as genes encoding chloramphenicol acetyltransferase and anti-gp120 single-chain Fv (artificially constructed to remove rare codons), were expressed at similar levels using with both tRNA preparations. On the other hand, the use of codon-plus tRNA increased the expression levels of genes having a relatively large number of the rare codons, including genes encoding archaeal proteins, green fluorescent protein of jelly fish origin, and a single-chain Fv of mouse origin, by about 20% higher than that using normal tRNA.
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PMID:Dosage effect of minor arginyl- and isoleucyl-tRNAs on protein synthesis in an Escherichia coli in vitro coupled transcription/translation system. 1623 46