Highly repressible expression system for cloning genes that specify potentially toxic proteins.
01 Oct 1987-Journal of Bacteriology (American Society for Microbiology)-Vol. 169, Iss: 10, pp 4457-4462
TL;DR: In this article, a highly repressible expression vector system that allows the cloning of potentially deleterious genes has been constructed and tested by measuring the inhibition of expression of traT, the gene for the TraT major outer membrane lipoprotein.
Abstract: A highly repressible expression vector system that allows the cloning of potentially deleterious genes has been constructed Undesired expression of a cloned gene was prevented (i) at the level of initiation of transcription, by the presence of the strong but highly repressible leftward promoter of bacteriophage lambda, lambda pL, and (ii) at the level of transcript elongation or translation, through synthesis of antisense RNA complementary to the mRNA of the cloned gene The system was tested by measuring the inhibition of expression of traT, the gene for the TraT major outer membrane lipoprotein Direct detection and functional assays indicated that an essentially complete inhibition of traT expression was obtained As a further test of the system, the gene encoding the EcoRI restriction endonuclease was cloned in the absence of the gene of the corresponding protective EcoRI modification methylase Transformants harboring this construct were only viable when both repression controls were operational
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TL;DR: The tight regulation of the PBAD promoter is exploited to study the phenotypes of null mutations of essential genes and the use of pBAD vectors as an expression system is explored.
Abstract: We have constructed a series of plasmid vectors (pBAD vectors) containing the PBAD promoter of the araBAD (arabinose) operon and the gene encoding the positive and negative regulator of this promoter, araC. Using the phoA gene and phoA fusions to monitor expression in these vectors, we show that the ratio of induction/repression can be 1,200-fold, compared with 50-fold for PTAC-based vectors. phoA expression can be modulated over a wide range of inducer (arabinose) concentrations and reduced to extremely low levels by the presence of glucose, which represses expression. Also, the kinetics of induction and repression are very rapid and significantly affected by the ara allele in the host strain. Thus, the use of this system which can be efficiently and rapidly turned on and off allows the study of important aspects of bacterial physiology in a very simple manner and without changes of temperature. We have exploited the tight regulation of the PBAD promoter to study the phenotypes of null mutations of essential genes and explored the use of pBAD vectors as an expression system.
4,997 citations
TL;DR: Progress in the understanding of several biological processes promises to broaden the usefulness of Escherichia coli as a tool for gene expression and the remarkable increase in the availability of fusion partners offers a wide range of tools for improved protein folding, solubility, protection from proteases, yield, and secretion into the culture medium.
1,156 citations
TL;DR: The cloning of gene, ompH, is reported, which encodes a major pressure-inducible protein of strain SS9, a gram-negative eubacterium isolated from a depth of 2.5 kilometres in the Sulu Sea, and the function of the OmpH protein in adaptation to high pressure and the use of the oMPH gene in studying how bacteria sense and respond to pressure is discussed.
Abstract: Barophilic bacteria inhabit the deep oceans, and the specific functional modifications and regulatory mechanisms which govern adaptation to hydrostatic pressure are beginning to be understood. For example, the rate of production of several proteins by some hydrothermal vent archaebacteria and the degree of saturation of membrane lipids in other deep-sea bacteria have been found to change as a result of cultivation at high pressure. We report here the cloning of gene, ompH, which encodes a major pressure-inducible protein of strain SS9, a gram-negative eubacterium isolated from a depth of 2.5 kilometres in the Sulu Sea. Messenger RNA encoded by ompH is expressed when cells are grown at 280 atm but not at 1 atm, indicating that transcription of the ompH gene is controlled by hydrostatic pressure. The function of the OmpH protein in adaptation to high pressure and the use of the ompH gene in studying how bacteria sense and respond to pressure is discussed.
160 citations
TL;DR: The properties and sources of all known class-I, class-II and class-III restriction endonucleases (ENases) and DNA modification methyltransferases (MTases) are listed and newly subclassified according to their sequence specificity.
153 citations
TL;DR: A functional analysis of the 16 putative Type II R-M systems in the H. pylori J99 genome is described, which found that <30% of the potential Type I R- M systems in H.pyloriJ99 strain were fully functional, displaying both endonuclease and methyltransferase activities.
Abstract: Helicobacter pylori is a gram-negative bacterium, which colonizes the gastric mucosa of humans and is implicated in a wide range of gastroduodenal diseases. The genomic sequences of two H.pylori strains, 26695 and J99, have been published recently. About two dozen potential restriction–modification (R-M) systems have been annotated in both genomes, which is far above the average number of R-M systems in other sequenced genomes. Here we describe a functional analysis of the 16 putative Type II R-M systems in the H.pylori J99 genome. To express potentially toxic endonuclease genes, a unique vector was constructed, which features repression and antisense transcription as dual control elements. To determine the methylation activities of putative DNA methyltransferases, we developed polyclonal antibodies able to detect DNA containing N6-methyladenine or N4-methylcytosine. We found that <30% of the potential Type II R-M systems in H.pylori J99 strain were fully functional, displaying both endonuclease and methyltransferase activities. Helicobacter pylori may maintain a variety of functional R-M systems, which are believed to be a primitive bacterial ‘immune’ system, by alternatively turning on/off a subset of numerous R-M systems.
145 citations
References
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Book•
15 Jan 2001
TL;DR: Molecular Cloning has served as the foundation of technical expertise in labs worldwide for 30 years as mentioned in this paper and has been so popular, or so influential, that no other manual has been more widely used and influential.
Abstract: Molecular Cloning has served as the foundation of technical expertise in labs worldwide for 30 years. No other manual has been so popular, or so influential. Molecular Cloning, Fourth Edition, by the celebrated founding author Joe Sambrook and new co-author, the distinguished HHMI investigator Michael Green, preserves the highly praised detail and clarity of previous editions and includes specific chapters and protocols commissioned for the book from expert practitioners at Yale, U Mass, Rockefeller University, Texas Tech, Cold Spring Harbor Laboratory, Washington University, and other leading institutions. The theoretical and historical underpinnings of techniques are prominent features of the presentation throughout, information that does much to help trouble-shoot experimental problems. For the fourth edition of this classic work, the content has been entirely recast to include nucleic-acid based methods selected as the most widely used and valuable in molecular and cellular biology laboratories. Core chapters from the third edition have been revised to feature current strategies and approaches to the preparation and cloning of nucleic acids, gene transfer, and expression analysis. They are augmented by 12 new chapters which show how DNA, RNA, and proteins should be prepared, evaluated, and manipulated, and how data generation and analysis can be handled. The new content includes methods for studying interactions between cellular components, such as microarrays, next-generation sequencing technologies, RNA interference, and epigenetic analysis using DNA methylation techniques and chromatin immunoprecipitation. To make sense of the wealth of data produced by these techniques, a bioinformatics chapter describes the use of analytical tools for comparing sequences of genes and proteins and identifying common expression patterns among sets of genes. Building on thirty years of trust, reliability, and authority, the fourth edition of Mol
215,169 citations
TL;DR: A method has been devised for the electrophoretic transfer of proteins from polyacrylamide gels to nitrocellulose sheets that results in quantitative transfer of ribosomal proteins from gels containing urea.
Abstract: A method has been devised for the electrophoretic transfer of proteins from polyacrylamide gels to nitrocellulose sheets. The method results in quantitative transfer of ribosomal proteins from gels containing urea. For sodium dodecyl sulfate gels, the original band pattern was obtained with no loss of resolution, but the transfer was not quantitative. The method allows detection of proteins by autoradiography and is simpler than conventional procedures. The immobilized proteins were detectable by immunological procedures. All additional binding capacity on the nitrocellulose was blocked with excess protein; then a specific antibody was bound and, finally, a second antibody directed against the first antibody. The second antibody was either radioactively labeled or conjugated to fluorescein or to peroxidase. The specific protein was then detected by either autoradiography, under UV light, or by the peroxidase reaction product, respectively. In the latter case, as little as 100 pg of protein was clearly detectable. It is anticipated that the procedure will be applicable to analysis of a wide variety of proteins with specific reactions or ligands.
53,030 citations
Book•
01 Jan 1972
TL;DR: Molecular Genetics (Biology): An Overview | Sciencing Experimental in Molecular Genetics Experiments in molecular genetics (1972 edition) | Open ...
Abstract: Molecular Genetics (Biology): An Overview | Sciencing Experiments in Molecular Genetics Experiments in molecular genetics (1972 edition) | Open ... Experimental Molecular Genetics | Biology | MIT OpenCourseWare DNA experiments you can perform at home | SBS Science Experiments in molecular genetics Jeffrey H. Miller ... DNA and Molecular Genetics Experiments in Molecular Biology: Biochemical Applications ... Molecular Genetics Biology Experiment Please help ... Molecular genetics | biology | Britannica Molecular Genetic Experiment : Biology Lab 1793 Words ... Miller, J.H. (1972) Experiments in Molecular Genetics ... Griffith's experiment Wikipedia DNA as genetic material: Revisiting classic experiments ... Experiments in molecular genetics (Book, 1972) [WorldCat.org] Measuring βGalactosidase Activity in Bacteria: Cell ... Classic Experiments in
26,898 citations
TL;DR: New Escherichia coli host strains have been constructed for the E. coli bacteriophage M13 and the high-copy-number pUC-plasmid cloning vectors and mutations introduced into these strains improve cloning of unmodified DNA and of repetitive sequences.
14,954 citations
TL;DR: A series of plasmid vectors containing the multiple cloning site (MCS7) of M13mp7 has been constructed and a kanamycin-resistance marker has been inserted into the center of the symmetrical MCS7 to yield a restriction-site-mobilizing element (RSM).
5,719 citations