Disease relevance of galK

• Fusion of the Escherichia coli tRNALeu1 promoter to the galK gene: analysis of sequences necessary for growth-rate-dependent regulation [1].
• Employing specifically engineered plasmids in which the expression of E. coli galK cistron is regulated by transcription termination, we have analyzed the antitermination function of phage lambda N gene product in S30 extracts [2].
• Plasmids were constructed with and without interposition of the rho-independent coliphage T7 'early' terminator between a promoter and galK [3].
• The potential use of the galK fusion system to isolate and characterize Streptomyces transcription signals is discussed [4].
• A plasmid with the galK gene under control of the promoter of the mannitol utilization genes (mtl) from Pseudomonas fluorescens DSM 50106 was constructed to isolate the mtl regulatory gene [5].

High impact information on galK

• In vivo, RNA I controls plasmid copy number and incompatibility and inhibits expression of a galK gene fused to the primer promoter [6].
• We have fused DNA fragments derived from an Escherichia coli tRNALeu1 operon to the galK gene of E. coli to identify sequences necessary for the in vivo initiation of transcription and growth-rate-dependent regulation [1].
• Constructions were characterized that allow ribosomes to stop selectively before, within or downstream from the galK initiation signal [7].
• This fragment mediated antitermination of transcription at 30 degrees C, as measured by assaying galK gene expression in Escherichia coli [8].
• The transfected Drosophila S2 cell lines expressed high levels of both galK mRNA and protein in response to metal induction [9].

Chemical compound and disease context of galK

• All three strains contain an otherwise complete galactose operon, except for a precise deletion of the galK gene, and a defective temperature-sensitive lambda prophage that makes recombineering possible [10].
• The effect of the DNA gyrase inhibitor, nalidixic acid, on expression from E. coli promoters was studied using the pKO-1, galactokinase expression vector system [11].
• Pyrococcus furiosus galactokinase was cloned, expressed in Escherichia coli, purified and crystallized using the hanging-drop method of vapour diffusion with ammonium sulfate as the precipitant [12].
• A collection of variant plasmids expressing either Escherichia coli galactokinase or human serum albumin under the control of several E. coli trp promoter derivatives were constructed and studied for both efficiency of expression and regulation by tryptophan [13].
• METHODS: Diagnoses were based on thin layer chromatography for galactosuria/galactosemia and assays of erythrocyte galactose-1-phosphate uridyltransferase (GALT) and galactokinase activities [14].

Biological context of galK

• Other three incomplete open reading frames showing homology to another beta-galactosidase, an alpha-galactosidase, and a galactokinase, respectively, were also found [15].
• Promoter sequences consisting of residues from -50 to +56 or -50 to +5 with respect to the in vivo site for initiation of transcription were introduced into chimeric plasmids upstream from the galK gene [1].
• Deletions constructed in the promoter region of pPYRB10 from the 3' side produced one plasmid that retained normal control of galK expression and five that exhibited greatly reduced regulation [16].
• In addition, we placed these upstream inserted AUG codons into each of the three possible translation reading frames so that translation occurring in these frames terminates prior to, within, or downstream of the galK initiation codon, respectively [17].
• The substrate DNAs were incubated in an in vitro SV40 DNA replication system and used to transform the E. coli galK strain DH10B after digestion with DpnI [18].

Anatomical context of galK

• Galactokinase activity and growth sensitivity to 2-DOG could be restored by transfecting H12.10 cells with a plasmid containing the Escherichia coli galactokinase (galK) gene fused to a eucaryotic promoter; thus, the 2-DOG selection could be directed against transfected recombinant constructs in a liver cell line [19].

Associations of galK with chemical compounds

• Cells bearing these chimeric plasmids exhibited much higher levels of galactokinase than did cells bearing plasmids wherein the galactose promoter was fused to galK [1].
• However, when the trp t hairpin is placed between galK and a downstream copy of trp t', galactokinase levels are enhanced 2- to 3-fold [20].
• Sequences consisting of the 17-bp nutL core flanked by two HindIII cohesive sites were synthesized by the phosphite coupling method, and cloned in proper orientation between the Pp promoter of pBR322 and lambda gene N followed by the tL1 terminator on a galK-expression plasmid [21].
• (4) Polyacrylamide gel patterns of restriction digests of the pK0482 mutated at the galK gene were indistinguishable from those of the unmutated plasmid DNA [22].
• Transformants were selected by ampicillin resistance and mutations were analyzed simultaneously by the altered expression of the galK gene [22].

Other interactions of galK

• The effect of supercoiling in vivo was analysed by measuring the activity of the tyrT promoter on a galK fusion vector in E. coli strains that have mutations in either the DNA gyrase or topoisomerase I genes [23].
• Fusion of a 120-base pair fragment, containing 90 base pairs of DNA upstream of the sodA transcription initiation site, to a promoterless galactokinase gene (galK) conferred redox-sensitivity to GalK synthesis [24].
• However, when lambda N protein is provided, and if a functional N interaction site, nutR, is intact, transcription antitermination occurs and galK expression increases [25].
• To locate the site required for transcription antitermination by the gene Q product, we constructed a plasmid containing the p'R promoter, the t'R1 terminator, and gene galK [26].

Analytical, diagnostic and therapeutic context of galK

• Because parts of the gene for the mutarotase as well as the promoter region upstream of galK were not cloned on pKBL1, the regions flanking the HindIII fragment of pKBL1 were amplified by inverse PCR [27].
• (2) This fragment was partially purified by agarose gel electrophoresis, ligated into the BamHI site of pBR322 and transformed into Escherichia coli to generate a clone bank containing the galactokinase gene [28].
• In this publication we show that galactokinase synthesis is turned on by aflatoxin B1 metabolites within an hour after treatment of the tester bacteria [29].
• Cloning, purification, crystallization and preliminary crystallographic analysis of galactokinase from Pyrococcus furiosus [12].
• The monomer Mr is 160,000 as judged from sodium dodecyl sulfate/polyacrylamide gel electrophoresis and the native Mr has been calculated to be 600,000-650,000 from gel filtration experiments. beta-Galactosidase/galactokinase has different thermostability curves, pH/activity profiles and Km values as compared with the native enzymes [30].

References