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Lac Operon (lac + operon)
Selected AbstractsActivity of Serratia plymuthica IC1270 gene chiA promoter region in Escherichia coli mutants deficient in global regulators of transcriptionJOURNAL OF BASIC MICROBIOLOGY, Issue 6 2005I. A. Khmel To study the regulation of expression of the Serratia plymuthica gene chiA encoding a 58-kDa endochitinase, its 586-bp-long upstream regulatory region was cloned, sequenced and fused to a promoterless lac operon in phage ,RS45 to obtain a single-copy transcriptional fusion (PF1chiA - lac ) in lysogens of Escherichia coli wild-type strains or their mutants deficient in various global regulators of transcription. The level of PF1chiA - lac expression increased about 20- and 90-fold, respectively, in E. coli K12 ,hns and double ,hns stpA mutants deficient in H-NS, and in both H-NS and StpA DNA-binding histone-like proteins, as compared to levels in the wild-type strain. In a ,lrp mutant deficient in the leucine-responsive transcriptional regulator Lrp, the level of PF1chiA - lac expression increased only up to threefold, whereas even smaller differences relative to the wild-type strain were observed in rpoS and ,crp mutants deficient in the ,S subunit of RNA polymerase and catabolite-repression protein (CRP), respectively. Deletion of the inverted-repeat sequences and curved DNA regions located in the upstream region of chiA essentially did not influence strain IC1270's chiA promoter activity in E. coli . (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Binding properties of peptidic affinity ligands for plasmid DNA capture and detectionAICHE JOURNAL, Issue 2 2009Ying Han Abstract Peptides constructed from ,-helical subunits of the Lac repressor protein (LacI) were designed then tailored to achieve particular binding kinetics and dissociation constants for plasmid DNA purification and detection. Surface plasmon resonance was employed for quantification and characterization of the binding of double stranded Escherichia coli plasmid DNA (pUC19) via the lac operon (lacO) to "biomimics" of the DNA binding domain of LacI. Equilibrium dissociation constants (KD), association (ka), and dissociation rates (kd) for the interaction between a suite of peptide sequences and pUC19 were determined. KD values measured for the binding of pUC19 to the 47mer, 27mer, 16mer, and 14mer peptides were 8.8 ± 1.3 × 10,10 M, 7.2 ± 0.6 × 10,10 M, 4.5 ± 0.5 × 10,8 M, and 6.2 ± 0.9 × 10,6 M, respectively. These findings show that affinity peptides, composed of subunits from a naturally occurring operon,repressor interaction, can be designed to achieve binding characteristics suitable for affinity chromatography and biosensor devices. © 2008 American Institute of Chemical Engineers AIChE J, 2009 [source] Synthesis of new S -glycodendrimer toward activation of lac operon transcription for protein biosynthesisJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 1 2009Akinori Takasu To enable gene transcription or lac operon transcription, isopropyl ,- D -thiogalactoside (IPTG) and allolactose can bind to the lac repressor. New S -glycodendrimers for activation of the lac operon were synthesized by S -glycosidation and DCC-HOBt coupling with a poly(amidoamine) dendrimer. Expression of artificial protein was performed for Escherichia coli using these glycodendrimers as the inducers. Cells encoded with green fluorescent protein (GFP) were induced with the glycoconjugates. After expression at 37 °C for 4 h, fluorescence emissions were actually observed through visual observation, which indicated that S -glycodendrimer acted as an inducer for protein biosynthesis. Quantitative analysis using fluorescence spectrometer was carried out to evaluate the activity. [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.] [source] Response to culture aeration mediated by the nitrate and nitrite sensor NarQ of Escherichia coli K-12MOLECULAR MICROBIOLOGY, Issue 4 2003Valley Stewart Summary Respiratory enzyme synthesis in enterobacteria is controlled in response to electron acceptor availability. The iron,sulphur protein Fnr and the sensor,regulator proteins ArcB,ArcA control respiratory gene transcription in response to oxygen and quinone pool redox status respectively. The sensor,regulator proteins NarX,NarL and NarQ,NarP control anaerobic respiratory gene expression in response to nitrate and nitrite. Our laboratory recently engineered the lac operon to replace the primary operator O1- lac with the NarL and NarP protein binding site from the nirB operon. Expression of the lacZ gene from this construct is repressed by nitrate in Nar+ strains. Here, we found that lacZ gene expression was repressed in aerated cultures of narQ+narX null strains. This repression was not observed in narX+narQ+ or narX+narQ null strains. Thus, the NarQ sensor responds to aeration as well as to nitrate and nitrite. The NarX and NarQ sensors are composed of three distinct modules: an amino-terminal sensory module, a carboxyl-terminal transmitter module and a central module of unknown function. Experiments with NarX,NarQ hybrid proteins suggest that the NarQ protein central module is necessary for response to aeration. The physiological significance of this additional sensory role for the NarQ sensor remains obscure. [source] | ||||||||||