scholarly journals The role of Halobacterium cutirubrum deoxyribonucleic acid-dependent ribonucleic acid polymerase subunits in initiation and polymerization

1972 ◽  
Vol 127 (1) ◽  
pp. 81-86 ◽  
Author(s):  
B. Gregory Louis ◽  
P. S. Fitt
Keyword(s):  
Maximum Rate ◽  
Rna Synthesis ◽  
Deoxyribonucleic Acid ◽  
Marked Effect ◽  
Α Subunit ◽  
Bivalent Cations ◽  
Β Protein ◽  
Template Specificity

1. The two subunits α and β of Halobacterium cutirubrum DNA-dependent RNA polymerase are required in equimolar amounts for RNA synthesis to occur in vitro at the maximum rate. 2. In the absence of bivalent cations no interaction occurs between α and β subunits or between the subunits and DNA. 3. Mn2+ causes the subunits to form a 1:1 complex that still does not bind to the template. 4. Mg2+ permits binding of the Mn2+-mediated complex to DNA. 5. The complete enzyme, αβ, is inhibited by rifampicin and only the β subunit relieves the inhibition when added in excess. 6. Rifampicin-insensitive, template-dependent RNA synthesis occurs in the presence of protein α alone provided an oligonucleotide with a 5′-purine terminus is supplied as primer. 7. In the primed reaction with the α protein and an oligonucleotide, the template specificity is independent of the ionic strength, in contrast with the marked effect of salt concentration on the template specificity of the complete enzyme. 8. It is concluded that the β protein controls the specificity of chain initiation and the template specificity of the complete enzyme and also carries the rifampicin-binding site, whereas the catalytic site is on the α subunit.

scholarly journals The role of ATP in in vitro vaccinia virus RNA synthesis effects of AMP-PNP and ATP gamma S.

1980 ◽  
Vol 255 (11) ◽  
pp. 5396-5403
Author(s):  
S. Shuman ◽  
E. Spencer ◽  
H. Furneaux ◽  
J. Hurwitz
Keyword(s):  
Vaccinia Virus ◽  
Rna Synthesis ◽  
Virus Rna ◽  
Gamma S

Synthesis of acid-soluble spore proteins by Bacillus subtilis

1982 ◽  
Vol 152 (3) ◽  
pp. 1117-1125
Author(s):  
J M Leventhal ◽  
G H Chambliss
Keyword(s):  
Bacillus Subtilis ◽  
Maximum Rate ◽  
Rna Synthesis ◽  
Actinomycin D ◽  
Sodium Dodecyl ◽  
Molecular Weights ◽  
Spore Proteins ◽  
Major Acid

The major acid-soluble spore proteins (ASSPs) of Bacillus subtilis were detected by immunoprecipitation of radioactively labeled in vitro- and in vivo-synthesized proteins. ASSP synthesis in vivo began 2 h after the initiation of sporulation (t2) and reached its maximum rate at t7. This corresponded to the time of synthesis of mRNA that stimulated the maximum rate of ASSP synthesis in vitro. Under the set of conditions used in these experiments, protease synthesis began near t0, alkaline phosphatase synthesis began at about t2, and refractile spores were first observed between t7 and t8. In vivo- and in vitro-synthesized ASSPs comigrated in sodium dodecyl sulfate-polyacrylamide gels. Their molecular weights were 4,600 (alpha and beta) and 11,000 (gamma). The average half-life of the ASSP messages was 11 min when either rifampin (10 micrograms/ml) or actinomycin D (1 microgram/ml) was used to inhibit RNA synthesis.

Role of the Pepino mosaic virus 3′-untranslated region elements in negative-strand RNA synthesis in vitro

2014 ◽  
Vol 190 ◽  
pp. 110-117 ◽  
Author(s):  
Toba A.M. Osman ◽  
René C.L. Olsthoorn ◽  
Ioannis C. Livieratos
Keyword(s):  
Mosaic Virus ◽  
Untranslated Region ◽  
Rna Synthesis ◽  
Pepino Mosaic Virus ◽  
Negative Strand

Virulent bacteriophage infection of Rhizobium leguminosarum

1972 ◽  
Vol 18 (4) ◽  
pp. 375-384 ◽  
Author(s):  
A. N. Ley ◽  
H. R. Warner ◽  
Phyllis L. Kahn
Keyword(s):  
Molecular Weight ◽  
Rna Synthesis ◽  
Rhizobium Leguminosarum ◽  
Deoxyribonucleic Acid ◽  
In Vitro Assays ◽  
Tail Fiber ◽  
Bacteriophage Infection ◽  
Cell Extracts ◽  
High Level

Bacteriophage 317, which virulently infects Rhizobium leguminosarum, has an eclipse period of 60–70 min and a latent period of 100 min at 30°. Electron micrographs of the phage indicated head, tail, and tail-fiber structural components.Base analysis of phage 317 deoxyribonucleic acid (DNA) indicated the presence of equimolar amounts of adenine and thymine and of guanine and cytosine, which suggests that the DNA is double stranded. The DNA has a molecular weight of 41 × 106 daltons as determined from electron micrographs.The results of 14C-uracil incorporation studies showed that net ribonucleic acid (RNA) synthesis was markedly inhibited after infection. There was a slight stimulation in DNA synthesis after infection as indicated by 14C-thymidine incorporation.The results of in vitro assays of enzymes involved in the biosynthesis of DNA showed that deoxyuridine 5′-triphosphate nucleotidohydrolase (dUTPase) and deoxythymidine 5′-monophosphate kinase (dTMP kinase) increased 50- and 30-fold respectively, after infection. The reason for the increased dUTPase activity is not readily apparent. Phage 317 DNA contains only the standard bases, unlike the DNA of other phages that induce an increase in this enzyme after infection. A high level of deoxythymidine 5′-monophosphatase (dTMPase) was observed in both uninfected and infected crude cell extracts. Further work is necessary to see if similar changes occur in Rhizobium during the establishment of symbiosis with legumes.

scholarly journals Transcription of bacteriophage T4 deoxyribonucleic acid in vitro

1969 ◽  
Vol 115 (3) ◽  
pp. 353-361 ◽  
Author(s):  
John O. Bishop ◽  
Forbes W. Robertson
Keyword(s):  
Rna Polymerase ◽  
Messenger Rna ◽  
Rna Synthesis ◽  
Deoxyribonucleic Acid ◽  
Bacteriophage T4 ◽  
Rna Sequences ◽  
Experimental Conditions ◽  
E Coli ◽  
New Methods

1. RNA was synthesized in vitro from a template of bacteriophage T4 DNA, in the presence of Mn2+. A comparison was made of the RNA synthesized by purified RNA polymerase from two sources, Micrococcus lysodeikticus and Escherichia coli; these are referred to as Micrococcus cRNA and E. coli cRNA respectively (where cRNA indicates RNA synthesized in vitro by using purified RNA polymerase and a DNA primer). 2. Both types of RNA were self-complementary as judged by resistance to digestion with ribonuclease after self-annealing, Micrococcus cRNA being more self-complementary (40%) than was E. coli cRNA (30%). The cRNA was found to be much less self-complementary if Mg2+ was present during RNA synthesis instead of Mn2+. 3. Micrococcus cRNA hybridized with a larger part of bacteriophage T4 DNA than did E. coli cRNA. The E. coli cRNA competed with only part (70%) of the Micrococcus cRNA in hybridization-competition experiments. It is concluded that more sequences of bacteriophage T4 DNA are transcribed by Micrococcus polymerase than by E. coli polymerase. 4. The RNA sequences synthesized by Micrococcus RNA polymerase but not by E. coli RNA polymerase are shown by hybridization competition to compete with specifically late bacteriophage T4 messenger RNA sequences. The relevance of this finding to the control of transcription is discussed. 5. In an Appendix, new methods are described for the analysis of hybridization-saturation and -competition experiments. Particular attention is paid to the effects produced if different RNA sequences are present at different relative concentrations. 6. By using cRNA isolated from an enzymically synthesized DNA–RNA hybrid, it is estimated that, of the DNA that is complementary to cRNA, only about half can become hybridized with cRNA under the experimental conditions used.

Abstract 18708: Vascular Dysfunction in Hyperhomocysteinemia: In vitro Evidence for Endoplasmic Reticulum Stress-mediated Calcium-activated Potassium Channel Dysfunction

Circulation ◽  
2015 ◽  
Vol 132 (suppl_3) ◽  
Author(s):  
Wen-Tao Sun ◽  
Xiang-Chong Wang ◽  
Cheuk-Man Yu ◽  
Shun-Hay Pun ◽  
Qin Yang
Keyword(s):  
Endoplasmic Reticulum ◽  
Smooth Muscle ◽  
Cell Surface ◽  
Er Stress ◽  
Vascular Dysfunction ◽  
Cell Protein ◽  
Α Subunit ◽  
Whole Cell

Objectives: KCa channels play an important role in the control of vascular tone. Opening of IKCa and SKCa in endothelial cells underlies the classic EDHF pathway and promotes NO production. Smooth muscle BKCa provides a negative feedback mechanism opposing vasoconstriction and is an effector of NO and EDHF. Previous studies demonstrated homocysteine (Hcy), a risk factor for atherosclerosis, compromises NO and EDHF function, however, whether KCa is involved is poorly studied and the underlying mechanisms remain unknown. We studied the effect of Hcy on vascular KCa with the role of endoplasmic reticulum (ER) stress explored. Methods: In vitro studies were performed in porcine coronary arteries and primary cultured porcine coronary endothelial (PCECs) and smooth muscle cells (PCSMCs). IKCa and SKCa-, and BKCa-mediated relaxations were studied in endothelium-intact and -denuded arteries in a myograph. IKCa and SKCa currents in PCECs and BKCa current in PCSMCs were analyzed by whole-cell patch clamp and channel expressions were examined by western blot. Results: Hcy impairs the role of IKCa and SKCa, and BKCa in vasorelaxation. Relaxant responses to channel activators NS309 and NS1619 were attenuated and EDHF-type response was inhibited. Hcy suppressed IKCa and SKCa currents in PCECs and BKCa currents in PCSMCs. Inhibition of ER stress enhanced KCa currents and improved EDHF-type and channel activators-induced responses. Whole-cell protein levels of IKCa and SKCa remained unchanged in Hcy-exposed PCECs whereas IKCa and SKCa at cell surface were significantly decreased. Hcy lowered protein of β1 but not α subunit of BKCa in PCSMCs. The decrease in cell surface IKCa and SKCa and reduction of BKCa β1 were restored by ER stress inhibition. Further, inhibition of PERK increased BKCa β1 protein and enhanced BKCa current. Conclusion: ER stress mediates Hcy-induced vascular dysfunction through inhibition of KCa. Suppression of cell surface expression underlies ER stress-mediated IKCa and SKCa inhibition. Downregulation of BKCa β1 by PERK-ER stress pathway plays a key role in the loss of BKCa function. This study provides new mechanistic insights into the role of ER stress in vascular dysfunction. Supported by RGC GRF CUHK4774/12M & CUHK14118414, and NSFC 81200123.

scholarly journals QUANTITATIVE STUDIES OF PHYTOHEMAGGLUTININ-INDUCED DNA AND RNA SYNTHESIS IN NORMAL AND AGAMMAGLOBULINEMIC LEUKOCYTES

1967 ◽  
Vol 125 (5) ◽  
pp. 863-872 ◽  
Author(s):  
Douglass C. Tormey ◽  
Roberta Kamin ◽  
H. Hugh Fudenberg
Keyword(s):  
Ribonucleic Acid ◽  
Rna Synthesis ◽  
Deoxyribonucleic Acid ◽  
In Vitro Synthesis ◽  
Dna And Rna ◽  
Quantitative Studies ◽  
Precursor Synthesis ◽  
Dna And Rna Synthesis

Leukocytes from nine patients with acquired agammaglobulinemia were studied in vitro. Synthesis of deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) induced by phytohemagglutinin was measured by determination of the degree of incorporation of labeled precursor. Synthesis of both DNA and RNA was decreased in the agammaglobulinemic cells. The presence of an inhibitor in the patients' sera could not be demonstrated. These results suggest that the basic defect in agammaglobulinemia is cellular rather than humoral.

scholarly journals Role of the C-Terminal Domain of the Alpha Subunit of RNA Polymerase in LuxR-Dependent Transcriptional Activation of the lux Operon during Quorum Sensing

2002 ◽  
Vol 184 (16) ◽  
pp. 4520-4528 ◽  
Author(s):  
Angela H. Finney ◽  
Robert J. Blick ◽  
Katsuhiko Murakami ◽  
Akira Ishihama ◽  
Ann M. Stevens
Keyword(s):  
Quorum Sensing ◽  
Rna Polymerase ◽  
Transcriptional Activation ◽  
Homoserine Lactone ◽  
Dependent Manner ◽  
Α Subunit ◽  
Terminal Domain

ABSTRACT During quorum sensing in Vibrio fischeri, the luminescence, or lux, operon is regulated in a cell density-dependent manner by the activator LuxR in the presence of an acylated homoserine lactone autoinducer molecule [N-(3-oxohexanoyl) homoserine lactone]. LuxR, which binds to the lux operon promoter at a position centered at −42.5 relative to the transcription initiation site, is thought to function as an ambidextrous activator making multiple contacts with RNA polymerase (RNAP). The specific role of the α-subunit C-terminal domain (αCTD) of RNAP in LuxR-dependent transcriptional activation of the lux operon promoter has been investigated. The effects of 70 alanine substitution variants of the α subunit were determined in vivo by measuring the rate of transcription of the lux operon via luciferase assays in recombinant Escherichia coli. The mutant RNAPs from strains exhibiting at least twofold-increased or -decreased activity in comparison to the wild type were further examined by in vitro assays. Since full-length LuxR has not been purified, an autoinducer-independent N-terminally truncated form of LuxR, LuxRΔN, was used for in vitro studies. Single-round transcription assays were performed using reconstituted mutant RNAPs in the presence of LuxRΔN, and 14 alanine substitutions in the αCTD were identified as having negative effects on the rate of transcription from the lux operon promoter. Five of these 14 α variants were also involved in the mechanisms of both LuxR- and LuxRΔN-dependent activation in vivo. The positions of these residues lie roughly within the 265 and 287 determinants in α that have been identified through studies of the cyclic AMP receptor protein and its interactions with RNAP. This suggests a model where residues 262, 265, and 296 in α play roles in DNA recognition and residues 290 and 314 play roles in α-LuxR interactions at the lux operon promoter during quorum sensing.

Sign in / Sign up

Export Citation Format

Share Document