Download or read book A Genetic and Biochemical Analysis of Attenuation Regulation in the Threonine Operon of Escherichia Coli K12 written by Steven Paul Lynn and published by . This book was released on 1988 with total page 456 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Analysis of the Effect of Mutations in the Leader Region of the Threonine Operon of Escherichia Coli on Attenuation Or Transcription Termination written by Harlan Bernard Scott (II) and published by . This book was released on 1991 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The expression of the threonine operon of Escherichia coli is controlled by attenuation. An open translational reading frame in the leader region preceding the structural genes contains 21 codons with eight threonine and four isoleucine codons. The model for attenuation proposes that regulation depends on the translation of the 21 amino acid leader peptide. Oligonucleotide-directed mutagenesis was used to introduce mutations into the leader region. Thirty-nine mutants were isolated. The effects of individual mutations on regulation were studied by making fusions to the lacZ gene, reducing the plasmid copy number, and assaying for the $beta$-galactosidase activity. Five mutants with two frameshift mutations each were constructed. The double frameshift mutants changed the leader peptide in two ways. First, the mutants had differing numbers of threonine and isoleucine codons. Second, the mutants had the threonine and isoleucine codons changed to differing numbers of histidine codons. Changing three threonine and one isoleucine codons abolished regulation by excess threonine and isoleucine. The presence of two histidine codons derepressed the operon in a hisT::Km background. Three mutations that would be predicted to block the translation of the normal leader peptide were constructed. All three mutants showed loss of regulation. The attenuator in the leader region encodes a rho-independent terminator. The terminator consists of a stem-loop structure with six bases in the loop and eight basepairs in the stem. The stem-loop is followed by nine rU residues and preceded by six rA residues. Various mutations in the threonine attenuator were assayed for their effects on transcription termination efficiency. As the number of rU residues in the terminator decreased from eight to one, the termination efficiency decreased. As the number of rA residues preceding the stem decreased from eight to one, the termination efficiency slightly increased. The sequence of the loop was also found to have a slight affect on termination efficiency. The sequences distal to the rU residues, which were non-transcribed, also had a slight affect on termination efficiency. Finally, a combination of changes in the stem with a change either in the loop or sequences distal to the rU residues had an affect on termination efficiency.
Download or read book Cloning of the Threonine Operon in Escherichia Coli K 12 written by Marianne Franck and published by . This book was released on 1986 with total page 150 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Genetic and Biochemical Studies on the Tryptophan Operon of Escherichia Coli written by Barbara Beckett Jones and published by . This book was released on 1975 with total page 444 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Regulation of Gene Expression in Escherichia coli written by E. C. C. Lin and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 1010 pages. Available in PDF, EPUB and Kindle. Book excerpt: This up-to-date guide focuses on the understanding of key regulatory mechanisms governing gene expression in Escherichia coli. Studies of E. coli not only provide the first models of gene regulation, but research continues to yield different control mechanisms.
Download or read book Research Awards Index written by and published by . This book was released on 1989 with total page 776 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Analysis of the Effect of Mutations in the Leader Region of the Threonine Operon of Escherichia Coli on Attenuation Or Transcription Termination written by Harland Bernard Scott and published by . This book was released on 1991 with total page 244 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Operon written by Jeffrey H. Miller and published by . This book was released on 1978 with total page 474 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Studies of the Molecular Mechanism of Attenuation in the Threonine Operon of Escherichia Coli Using Site directed Mutagenesis written by Ali Roghani and published by . This book was released on 1986 with total page 352 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dissertation Abstracts International written by and published by . This book was released on 1988 with total page 640 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Study of the Molecular Mechanism of the Attenuation Response in the Threonine Operon of Escherichia Coli by Synthesis of Mutant Attenuators written by William Seymour Burton and published by . This book was released on 1989 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt: To study the role of the competing terminator and antiterminator RNA structures in attenuation regulation of the thr operon of Escherichia coli, nine related attenuators with altered symmetry were made. Transfersions that destroy or invert a base pair near the middle of the base paired regions of the alternative stem-and-loop structures of the thr regulatory region were created to examine the role of the competing secondary structures in the attenuation response. The variants include the wild type; substitution mutants 106C, 136G and 155C; the three corresponding double mutants, 106C/136G, 106C/155C, and 136G/155C; the triple mutant, 106C/136G/155C; and a single-base deletion at position 106 (106$Delta$). The frameshift mutation removes the leader translation stop codon to determine whether unstopped ribosomes translating the distal regulatory region interfere with terminator function. All nine variants, including the wild type control, bear a deletion of position 165 as an artifact arising from the gene synthesis ligations. The mutants were fused to a lacZ sequence and stably integrated into the E. coli chromosome. Consistent with the proposed role for each of the alternative structures, assays of the variants showed that destabilization of the terminator hairpin caused increased expression, while disruption of the antiterminator caused decreased expression. Stability effects in the antiterminator were not observed, however, when the terminator was destabilized. Inverted base pairs functioned well in their respective hairpin structures, and the triple mutant exhibited wild type activity levels. All terminator mutations abolished the regulatory response to amino acid availability; the regulation was restored when the corresponding base change in the antiterminator restabilized the terminator structure. The frameshift mutant has increased expression and cannot regulate expression in response to differences in amino acid levels. DNA templates bearing the eight substitution mutations were transcribed in a purified RNA polymerase system with the goal of assessing their intrinsic termination efficiencies. In transcription assays performed with GTP, mutational effects were slight and did not correlate with terminator hairpin stability. Transcriptions performed with ITP in place of GTP produced lower termination efficiencies that varied not only with terminator stability, but also with antiterminator stability; the mutational effects paralleled those observed in vivo.
Download or read book Genetic and Physical Studies on the Regulation of the L arabinase Operon of Escherichia Coli K12 written by Brenda Rae Smith and published by . This book was released on 1978 with total page 238 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Biomedical Index to PHS supported Research written by and published by . This book was released on 1990 with total page 866 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book American Doctoral Dissertations written by and published by . This book was released on 1990 with total page 768 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Cumulated Index Medicus written by and published by . This book was released on 1982 with total page 1020 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Index to American Doctoral Dissertations written by and published by . This book was released on 1989 with total page 1252 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Genetics Abstracts written by and published by . This book was released on 1989 with total page 776 pages. Available in PDF, EPUB and Kindle. Book excerpt:
