Disease relevance of Lac Operon

• By equilibrium competition experiments, the dissociation constant (K(RD)) of lac repressor for E. coli DNA carrying a deletion of the lac operon was measured at a variety of salt concentrations [1].
• Fusions of the lac operon to genes induced by treatment with sublethal levels of alkylating agents have been selected from random insertions of the Mu-dl(ApRlac) phage by screening for induction of beta-galactosidase activity in the presence of methyl methanesulfonate [2].
• The gene encoding the repressor protein of the lac operon was integrated into the vaccinia virus genome so that it was expressed constitutively, and the lac operator was inserted next to the promoter of a gene that encodes an 11-kDa virion-associated protein of unknown function [3].
• Expression vectors have been constructed in which the mouse mammary tumor virus gag-pro frameshift region is placed upstream of the lacZ gene or the CUP1 gene so that the reporters are in the -1 frame relative to the initiation codon [4].
• Polymerase chain reaction-amplified fragments from the bacterial lacZ gene expressing up to 282 amino acids were added either to the amino- or carboxy-terminus of the DHBV core protein [5].

High impact information on Lac Operon

• To decipher its role in vivo we produced null mice by replacing Otx1 with the lacZ gene [6].
• Following the establishment of micrometastases, delivery of retroviral producer cells by the same route with a vector containing the Escherichia coli beta-galactosidase (lacZ) gene demonstrated selective in vivo gene transfer to tumour deposits [7].
• G207 has deletions at both gamma 34.5 (RL1) loci and a lacZ gene insertion inactivating the ICP6 gene (UL39) [8].
• We generated Fyn-deficient mice by inserting the beta-galactosidase gene (lacZ) into the fyn gene [9].
• We have investigated this possibility further and describe here the generation and characterization of a set of fusions of the lac genes to the promoter of the uvrA gene [10].

Chemical compound and disease context of Lac Operon

• We investigated cooperative repression of the Escherichia coli lac operon by systematic conversion of its three natural operators (O1, O2 and O3) on the chromosome [11].
• However, it is possible to select lactose carrier mutants that have an enhanced ability to transport maltose by growing E. coli cells on maltose minimal plates in the presence of isopropyl thiogalactoside (an inducer of the lac operon) [12].
• To test this approach, we examine the cross-linking in Escherichia coli of RNA polymerase to a constitutively expressed, lambda cI gene, and to the uninduced and isopropyl beta-D-thiogalactoside (IPTG)-induced lac operon [13].
• When HT1080 human fibrosarcoma cells marked with a lacZ gene (LZ+5) were cocultured with HT1080 cells transduced with a retrovirus expressing HSVtk (HT1080tk11), at a density at which the majority of cells were in contact, both HT1080tk11 and LZ+5 cells were killed by ganciclovir [14].
• The formation of SRN assessed by fluorescein angiography was more significantly inhibited for 7 days in the Adflt-ExR-treated rats than in the control rats who received either an adenovirus vector encoding LacZ gene or balanced salt solution (BSS) [15].

Biological context of Lac Operon

• We report that the SOS-inducible, error-prone DNA polymerase (pol) IV, encoded by dinB, is required for adaptive point mutation in the E. coli lac operon [16].
• The consequence of MLL truncation and fusion has been analysed by joining exon 8 of Mll with the bacterial lacZ gene using homologous recombination in mouse embryonic stem cells [17].
• By techniques of recombination in vitro, we have constructed a plasmid bearing the repressor gene (cI) of bacteriophage lambda fused to the promoter of the lac operon [18].
• Nucleotide sequences upstream of ziaA, fused to a promoterless lacZ gene, conferred Zn2+-dependent beta-galactosidase activity when introduced into R2-PIM8(smt) [19].
• The lac operon of Escherichia coli spans approximately 5300 base pairs and includes the lacZ, lacY, and lacA genes in addition to the operator, promoter, and transcription termination regions [20].

Anatomical context of Lac Operon

• By using the Cre-loxP recombination system we show that the mammary gland of whey acidic protein (WAP)-Cre/R26R mice, in which secretory epithelial cells express the lacZ gene during pregnancy, contains labeled adipocytes during involution [21].
• Successful transfer and expression of Lps(d)/Ran cDNA in endotoxin-sensitive C3H/HeOuJ macrophages reduced TNF-alpha production upon lipopolysaccharide (LPS) stimulation, as compared with macrophages transduced with vectors expressing the wild-type Lps(n)/Ran cDNA, the green fluorescent protein gene, or the lacZ gene [22].
• To examine the feasibility of this strategy, pActLacZ, an expression vector composed of the LacZ gene driven by the beta-actin promoter, complexed with lipofectin, was injected retrogradely into the common bile ducts of adult rats [23].
• Using primary neural crest cell cultures from embryos homozygous for a Kit null allele marked by an inserted LacZ gene (Kit(W-LacZ)), we show that the onset of Mitf expression in melanoblasts does not require KIT [24].
• To elucidate the signaling mechanism initiated by ARIA, we established stable C2C12 cell lines carrying the nuclear lacZ gene under the control of the mouse epsilon subunit promoter or chicken alpha subunit promoter [25].

Associations of Lac Operon with chemical compounds

• This effect is not observed in cells lacking repressor or in the absence of the operator, and it is reversed by an inducer of the lac operon, namely isopropyl thiogalactoside (IPTG) [26].
• To characterize the mode of action of angiotensin II (Ang II) in cardiac remodeling, we generated chimeric mice that are made of both homozygous Ang II receptor type 1A gene (Agtr1a) null mutant cells and Agtr1a intact cells expressing the lacZ gene (ROSA26) [27].
• The SsrA-mediated tagging and proteolysis of LacI appears to play a role in cellular adaptation to lactose availability by supporting a rapid induction of lac operon expression [28].
• We also demonstrated that in yeast cells the O2 protein can activate expression of a lacZ gene containing a multimer of the O2 target sequence as part of its promoter, thus confirming its role as a transcriptional activator [29].
• The trp and lac operons are found to be stimulated at the transcriptional level by the presence of this nucleotide [30].

Gene context of Lac Operon

• Antibodies made against a MCSP-1 lacZ gene fusion protein stain granules of CTL and react on immunoblots with two distinct granule protein bands of 29 and 35-40 kD [31].
• If an insert is an ORF of the correct length, ompF and lacZ become realigned in frame, resulting in a LacZ+ gene that produces a tribrid protein with the translation product of the insert sandwiched between OmpF and beta-galactosidase [32].
• We report here the sequence of the lacA gene and the region distal to it, confirming the sequence of thiogalactoside transacetylase and completing the sequence of the lac operon [20].
• One set of cells contained a lacY mutation and the other a deletion of the entire lac operon [33].
• We show that the MAT alpha UAS is sufficient to activate transcription from a promoterless gene fusion of the yeast CYC1 upstream region and the lacZ gene [34].

Analytical, diagnostic and therapeutic context of Lac Operon

• Expression of the lacZ gene was confirmed by X-Gal chromagen staining and visualization by light and transmission electron microscopy [35].
• Expression in cerebellar granule cells of RIIbeta and AKAP75 genes by microinjection of specific expression vectors, markedly stimulated cAMP-induced transcription of the lacZ gene driven by a cAMP-responsive element promoter [36].
• To this aim, C-26 cells were transduced, via retroviral vector, with the Escherichia coli LacZ gene and mixed tumor transplantation assays were performed by injecting a mixture of G-CSF-producing beta-gal- and G-CSF-nonproducing beta-gal+ C-26 cells at different ratios [37].
• In most fetuses expression of the LacZ gene was below the sensitivity of the X-gal staining, but expression was detected by PCR in 50%, 50% and 42% of the analyzed fetuses after adenoviral, plasmid/PEI and plasmid/liposome gene transfer, respectively [38].
• Twenty-two rats were given an acute wound and divided into two groups to receive weekly subcutaneous injections of liposomes plus the LacZ gene (0.2 microg, vehicle), or liposomes plus the KGF cDNA (2.2 microg) and LacZ cDNA (0.2 microg) [39].

References