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PubMed1977

Relationship between messenger ribonucleic acid and enzyme levels specified by the leucine operon of Escherichia coli K-12.

The levels of leucine-forming enzymes in Escherichia coli K-12 varied over a several thousand-fold range, depending upon conditions of growth. The highest levels were achieved by growing auxotrophs in a chemostat under conditions of leucine limitation. Under such conditions, enzyme levels were increased 45- to 90-fold relative to cells grown in minimal medium containing leucine (the latter values arbitrarily called 1). Leucine operon-specific messenger ribonucleic acid levels were elevated to about the same extent as enzyme levels in cells grown in a chemostat. Growth in media of greater complexity resulted in progressively lower levels of leucine-forming enzymes, reaching a value of less than 0.02 for growth in a medium containing tryptone broth and yeast extract. The levels of leucine operon-specified enzymes and messenger ribonucleic acid were also measured in strains containing about 25 copies of plasmid pCV1(ColE1-leu) per chromosome. For such strains grown in minimal medium, enzyme levels were proportional to the number of plasmids per cell. Furthermore, they followed the same trends as those described above upon derepression in a chemostat or upon repression following growth in rich media. Leucine messenger ribonucleic acid, measured both by pulse-labeling and hybridization-competition experiments, was roughly proportional to enzyme levels over this entire range. For a plasmid-containing strain grown in a chemostat under conditions of leucine limitation (about 100 plasmids per chromosome), about 27% of pulse-labeled ribonucleic acid was coded for by genes in or adjacent to the leucine operon, and 10% of the total protein was beta-isopropylmalate dehydrogenase.

2-Isopropylmalate Synthase↗
PubMed1995

Growth hormone receptor messenger ribonucleic acid expression in leiomyoma and surrounding myometrium.

OBJECTIVE: Uterine leiomyomas are the most common pelvic tumors, occurring in one of four women, and they represent the single most common indication for hysterectomy. The genesis and growth-promoting factors responsible for their development are poorly understood. We speculate that growth hormone may play a role in the initiation of these tumors; women with acromegaly have a higher incidence of leiomyomas and growth hormone promotes uterine growth in rats, with or without the addition of estradiol. We evaluated the presence of growth hormone receptor messenger ribonucleic acid in the human uterus and leiomyomas to investigate whether growth hormone might act directly rather than by hepatic generation of insulin-like growth factor-I. STUDY DESIGN: Paired samples of leiomyomas and adjacent normal myometrium from nine premenopausal women (32 to 52 years old) were collected at surgery. Three patients received a gonadotropin-releasing hormone agonist for 3 months before the surgical procedure; six did not receive any adjuvant therapy. We used a digoxigenin-labeled oligoprobe sharing no homology to the growth hormone-binding protein or to the prolactin receptor, to investigate whether growth hormone receptor messenger ribonucleic acid was present in tissue sections or amplified complementary deoxyribonucleic acid from leiomyoma and the surrounding myometrium. RESULTS: The ratios of growth hormone receptor/reduced glyceraldehyde-phosphate dehydrogenase in leiomyomas and the surrounding myometrium as assessed by densitometry analysis of polymerase chain reaction products were similar and were not altered by gonadotropin-releasing hormone agonist treatment. In situ hybridization localized the growth hormone receptor messenger ribonucleic acid to the nuclei and cytoplasm of leiomyoma and myometrium. CONCLUSION: The presence of growth hormone receptor messenger ribonucleic acid suggests that the human uterus is a target tissue for growth hormone action. Future investigations are needed to investigate further the role of growth hormone in the development of leiomyomas.

Adult↗
PubMed1969

Transcriptional mapping: functional organization of the ribosomal and transfer ribonucleic acid cistrons in the Bacillus subtilis genome.

The transcriptional mapping method developed previously has been used to investigate the functional organization of the ribosomal ribonucleic acid (rRNA) and transfer ribonucleic acid (tRNA) cistrons in the Bacillus subtilis genome. The sensitivities of the syntheses of these RNA species to actinomycin D indicated that (i) large polycistronic groupings of the tRNA cistrons exist, but (ii) the 16S and 23S rRNA cistrons are probably transcribed as individual units, and (iii) each 5S rRNA cistron is part of an operon containing a 23S rRNA cistron.

Bacillus subtilis↗
PubMed1966

Biochemical and genetic characterization of a mutant of Escherichia coli with a temperature-sensitive valyl ribonucleic acid synthetase.

Böck, August (Purdue University, Lafayette, Ind.), Lia Eidlic Faiman, and Frederick C. Neidhardt. Biochemical and genetic characterization of a mutant of Escherichia coli with a temperature-sensitive valyl ribonucleic acid synthetase. J. Bacteriol. 92:1076-1082. 1966.-To test our conclusion that Escherichia coli mutant I-9 possesses a valyl soluble ribonucleic acid (sRNA) synthetase that functions in vivo at 30 C but not at 37 C, measurements were made by use of the periodate method, of the level of charged valyl sRNA in this strain. A shift of temperature from 30 to 40 C resulted in a rapid discharging of valyl sRNA coordinate with the cessation of protein synthesis; at the same time, other species of sRNA, such as those for leucine, became fully charged. Identical results were obtained with a derivative of I-9 with relaxed ribonucleic acid (RNA) control. When P1 phage were grown on wild cells and then used at low multiplicities of infection to transduce temperature-resistant growth into I-9, complete cotransduction of normal valyl sRNA synthetase occurred. By means of the interrupted-mating technique, the structural gene for valyl sRNA synthetase was located on the E. coli chromosome map and found to be near thr, one-fifth of the length of the chromosome removed from the structural genes for the isoleucine-valine biosynthetic enzymes. Therefore, (i) the major valyl sRNA synthetase activity of I-9 appears to be temperature-sensitive in vivo, (ii) relaxed amino acid control over RNA synthesis does not appear to be a consequence of a normal charging of sRNA with a substitute molecule, and (iii) one structural gene for valyl sRNA synthetase is located on the E. coli chromosome not closely linked to the cistrons for the valine-biosynthetic enzymes.

Amino Acids↗
PubMed1977

Chemical measurement of steady-state levels of ten aminoacyl-transfer ribonucleic acid synthetases in Escherichia coli.

Polypeptide chains of 10 aminoacyl-transfer ribonucleic acid synthetases (those for arginine, glutamine, glutamic acid, glycine, isoleucine, leucine, lysine, phenylalanine, threonine, and valine) have been identified in lysates of Escherichia coli resolved by the O'Farrell two-dimensional gel system. By labeling cells uniformly with [14C]glucose and by measuring the total amounts of these polypeptides by their radioactivity, estimations of the steady-state, molecular amounts of these enzymes were made and compared to the number of ribosomes and elongation factors in these cells. Portions of a reference culture grown on glucose and labeled with [14C]leucine or [35S]sulfate were mixed with four cultures grown in widely different media containing [3H]leucine or [3H]leucine plus [3H]isoleucine. From the isotope ratios of the total protein and of the spots containing the synthetase chains, the chemical amount of each synthetase relative to that of the reference culture was determined. The results, where comparable, show reasonable agreement with enzyme activity measurements. In general, these synthetases each exhibit a positive correlation with growth rate in unrestricted media, indicating a strong tendency for the levels of transfer ribonucleic acid, synthetases, elongation factors, and ribosomes to remain approximately, though not exactly, in balance at different growth rates.

Alanine-tRNA Ligase↗
PubMed1981

Gene organization around the phenylalanyl-transfer ribonucleic acid synthetase locus in Escherichia coli.

The organization of seven genes located at about 38 min on the genetic map of Escherichia coli was examined; these genes included pheS and pheT, which code for the alpha and beta subunits of phenylalanyl-transfer ribonucleic acid synthetase, and thrS, the structural gene for threonyl-transfer ribonucleic acid synthetase. Deletion mutants were isolated from an F-prime-containing merodiploid strain and were characterized genetically. Seventeen different kinds of deletions extending into pheS of pheT were identified. These deletions unambiguously defined the gene order as aroD pps himA pheT pheS thrS pfkB. Mutants with deletions covering either pheS or pheT, but not both, were analyzed further by assay of phenylalanyl-transfer ribonucleic acid synthetase. The phenotype of the mutants with a deletion from pfkB through pheS was anomalous; although the pheT gene was apparently still present, its product, the beta subunit, was much reduced in activity.

Amino Acyl-tRNA Synthetases↗
PubMed1977

Temporal sequence of events during the initiation process in Escherichia coli deoxyribonucleic acid replication: roles of the dnaA and dnaC gene products and ribonucleic acid polymerase.

Three thermosensitive deoxyribonucleic acid (DNA) initiation mutants of Escherichia coli exposed to the restrictive temperature for one to two generations were examined for the ability to reinitiate DNA replication after returning to the permissive temperature in the presence of rifampin, chloramphenicol, or nalidixic acid. Reinitiation in the dnaA mutant was inhibited by rifampin but not by chloramphenicol, whereas renitiation was not inhibited by rifampin but not by chloramphenicol, whereas reinitiation was not inhibited in two dnaC mutants by either rifampin or chloramphenicol. To observe the rifampin inhibition, the antibiotic must be added at least 10 min before return to the permissive temperature. The rifampin inhibition of reinitiation was not observed when a rifampin-resistant ribonucleic acid ((RNA) polymerase gene was introduced into the dnaA mutant, demonstrating that RNA polymerase synthesizes one or more RNA species required for the initation of DNA replication (origin-RNA). Reinitiation at 30 degrees C was not inhibited by streptolydigin in a stretolydigin-sensitive dnaA muntant. Incubation in the presence of nalidixic acid prevented subsequent reinitiation in the dnaC28 mutant but did not inhibit reinitiation in the dnaA5 muntant. These results demonstrate that the dnaA gene product acts before or during the synthesis of an origin-RNA, RNA polymerase synthesizes this origin RNA, and the dnaC gene product is involved in a step after this RNA synthesis event. Furthermore, these results suggest that the dnaC gene product is involved in the first deoxyribounucleotide polymerization event wheareas the dnaA gene product acts prior to this event. A model is presented describing the temporal sequence of events that occur during initiation of a round of DNA replication, based on results in this and the accompanying paper.

Aminoglycosides↗
PubMed1969

Characteristics of the syrian hamster ribonucleic acid present in cells transformed by polyoma, simian virus 40, or adenovirus 12.

Ribonucleic acids of known specific activities were separately prepared from hamster cells transformed by polyoma, simian virus 40 (SV40), and adenovirus 12. When increasing amounts of these labeled ribonucleic acids were added to nitrocellulose filters containing immobilized (14)C-hamster deoxyribonucleic acid (DNA), about 5% of the DNA sites were saturated in each case. An additive saturation-hybridization experiment indicated that a portion of the 5% of the hamster DNA transcribed in SV40-transformed cells was also transcribed in polyoma-transformed cells. In addition, a separate region of the hamster genome was also transcribed in polyoma-transformed cells.

Adenoviridae↗
PubMed2005

Analysis of biological and synthetic ribonucleic acids by liquid chromatography-mass spectrometry using monolithic capillary columns.

Ion-pair reversed-phase high-performance liquid chromatography (IP-RP-HPLC) has been evaluated as a method for the fractionation and desalting of ribonucleic acids prior to their characterization by electrospray ionization mass spectrometry. Monolithic, poly(styrene-divinylbenzene)-based capillary columns allowed the rapid and highly efficient fractionation of both synthetic and biological ribonucleic acids. The common problem of gas-phase cation adduction that is particularly prevalent in the mass spectrometric analysis of ribonucleic acids was tackled through a combination of chromatographic purification and the addition of ethylenediaminetetraacetic acid to the sample at a concentration of 25 mmol/L shortly before on-line analysis. For RNA molecules ranging in size from 10 to 120 nucleotides, the mass accuracies were typically better than 0.02%, which allowed the characterization and identification of failure sequences and byproducts with high confidence. Following injection of a 500 nL sample onto a 60 x 0.2 mm column, the limit of detection for a 120-nucleotide ribosomal RNA transcript from Escherichia coli was in the 50-80 fmol range. The method was applied to the analysis of synthetic oligoribonucleotides, transfer RNAs, and ribosomal RNA. Finally, sequence information was derived for low picomole amounts of a 32-mer RNA upon chromatographic purification and tandem mass spectrometric investigation in an ion trap mass spectrometer. Complete series of fragment ions of the c- and y-types could be assigned in the tandem mass spectrum. In conclusion, IP-RP-HPLC using monolithic capillary columns represents a very useful tool for the structural investigation and quantitative determination of RNAs of synthetic and biological origin.

Chelating Agents↗
PubMed1965

Lifetime of bacterial messenger ribonucleic acid.

Moses, V. (University of California, Berkeley), and M. Calvin. Lifetime of bacterial messenger ribonucleic acid. J. Bacteriol. 90:1205-1217. 1965.-When cells from a stationary culture of Escherichia coli were placed in fresh medium containing inducer for beta-galactosidase, growth, as represented by increase in turbidity and by total protein synthesis, started within 30 sec. By contrast, beta-galactosidase synthesis was greatly delayed compared with induction during exponential growth. Two other inducible enzymes (d-serine deaminase and l-tryptophanase) and one repressible enzyme (alkaline phosphatase) showed similar lags. The lags were not due to catabolite repression. They could not be reduced by pretreatment of the culture with inducer, or by supplementing the fresh medium with amino acids or nucleotides. The lag was also demonstrated by an i(-) mutant constitutive for beta-galactosidase synthesis. An inhibitor of ribonucleic acid (RNA) synthesis, 6-azauracil, preferentially inhibited beta-galactosidase synthesis compared with growth in both inducible and constitutive strains. Puromycin, an inhibitor of protein synthesis, acted as an inhibitor at additional sites during the induction of beta-galactosidase synthesis. No inhibition of the reactions proceeding during the first 20 sec of induction was observed, but puromycin seemed to prevent the accumulation of messenger RNA during the period between 20 sec and the first appearance of enzyme activity after 3 min. It is suggested that these observations, together with many reports in the literature that inducible enzyme synthesis is more sensitive than total growth to some inhibitors and adverse growth conditions, can be explained by supposing that messenger RNA for normally inducible enzymes is biologically more labile than that for some normally constitutive proteins. The possible implications of this hypothesis for the achievement of cell differentiation by genetic regulation of enzyme synthesis are briefly discussed.

Chemical Phenomena↗
PubMed1973

Control of arginine biosynthesis in Escherichia coli: inhibition of arginyl-transfer ribonucleic acid synthetase activity.

In this study, we have extended our earlier observations indicating in vitro inhibition of arginyl-transfer ribonucleic acid synthetase (EC 6.1.13, arginine: soluble ribonucleic acid ligase, adenosine monophosphate) activity by the arginine biosynthetic precursors ornithine, citrulline, and argininosuccinate. Furthermore, we report evidence which suggest that this enzyme activity is inhibited by these arginine precursors in vivo and that this inhibition of activity results in a derepression of arginine biosynthesis.

Amino Acyl-tRNA Synthetases↗
PubMed1974

Properties and developmental roles of the lysyl- and tryptophanyl-transfer ribonucleic acid synthetases of Bacillus subtilis: common genetic origin of the corresponding spore and vegetative enzymes.

The lysyl-transfer ribonucleic acid synthetase (LRS) and tryptophanyl-transfer ribonucleic acid synthetases (TRS) (l-lysine:tRNA ligase [AMP], EC 6.1.1.6; and l-tryptophan:tRNA ligase [AMP], EC 6.1.1.2) have been purified 60- and 100-fold, respectively, from vegetative cells and spores of Bacillus subtilis. There are no significant differences between the corresponding spore and vegetative enzymes with respect to their elution characteristics from columns of phosphocellulose or hydroxylapatite, their molecular weight (~130,000 for LRS and ~87,000 for TRS as determined by gel filtration), their kinetic constants for substrates (in the amino acid-dependent adenosine triphosphate-pyrophosphate exchange reaction), and the kinetics of inactivation by heat and by antibody. The Mg(2+) requirement for optimal enzyme activity of the corresponding spore and vegetative enzyme differ slightly. Mutants having defective (temperature sensitive) vegetative LRS or TRS activities produce spores in which these enzymes are also defective. The mutant spores are more heat sensitive than the parental type, but contain normal levels of dipicolinic acid. They germinate normally at the restrictive temperature (43 C), but are blocked at specific developmental stages in outgrowth. No modification in temperature sensitivity phenotype occurs during outgrowth, nor is there a change in molecular weight of the two enzymes. The implication is that the LRS and TRS activities of the vegetative and spore stages are each coded (at least in part) by the same structural gene. The temperature sensitivity of mutant spores is discussed with respect to those factors which are involved in the formation of the heat-resistant state.

Amino Acyl-tRNA Synthetases↗
PubMed1970

Regulation of ribonucleic acid synthesis by histidine and methionine during recovery of Escherichia coli from magnesium starvation.

During magnesium starvation of Escherichia coli B, most of the ribosomes break down to low-molecular-weight components. When magnesium is restored to the medium, the cells recover. The rate of recovery can be increased greatly by supplementing the growth medium with a mixture of 21 amino acids. This increased rate of recovery is shown to be due to the effect of only two amino acids, histidine and methionine, which initially stimulate accumulation of cellular ribonucleic acid without increasing the rate of protein synthesis. In contrast, histidine and methionine supplementation to logarithmically growing E. coli B is not as effective in stimulating growth as is the complete amino acid mixture. Since cells recovering from magnesium starvation preferentially synthesize ribosomes, it is possible that histidine and methionine play a special role(s) in ribosomal ribonucleic acid synthesis or stability.

Amino Acids↗
PubMed1995

Interleukin-10 messenger ribonucleic acid in human placenta: implications of a role for interleukin-10 in fetal allograft protection.

OBJECTIVE: Our purpose was to determine whether interleukin-10 is expressed in human placental tissue, which might imply a role for it in fetal allograft protection. STUDY DESIGN: Detection of interleukin-10 messenger ribonucleic acid in human placental tissue and in human placental JAR cells by reverse transcription-coupled polymerase chain reaction was studied. RESULTS: Interleukin-10 messenger ribonucleic acid was detected in human placental tissue from term mothers and in human placental JAR cells. Sequence analysis of the expected interleukin-10 complementary deoxyribonucleic acid fragment revealed 100% homology to authentic interleukin-10 complementary deoxyribonucleic acid. CONCLUSION: Our results indicated that human placental tissue from term mothers expressed high levels of interleukin-10 messenger ribonucleic acid, suggesting that cells that produce interleukin-10 and that are associated with the placenta may play a role in preventing rejection of the fetal allograft by the mother.

Base Sequence↗
PubMed1996

Mutations in mitochondrial transfer ribonucleic acid genes in preeclampsia.

OBJECTIVE: We investigated whether maternally inherited mitochondrial deoxyribonucleic acid mutations could be associated with preeclampsia because mendelian models fail to explain all the aspects of inheritance in preeclampsia. STUDY DESIGN: In two families with a high occurrence of preeclampsia and eclampsia the 22 mitochondrial transfer ribonucleic acid genes were sequenced in eight and three women, respectively. RESULTS: An A-to-G mutation in transfer ribonucleic acidleu[UUR] at nucleotide 3243 was found in one family, and in the other there was an A-to-G mutation at nucleotide 12308 in transfer ribonucleic acidleu[CUN]. Mutations of mitochondrial transfer ribonucleic acid genes are generally considered to have systemic consequences, which might explain the multiorgan involvement seen in preeclampsia. CONCLUSION: We report for the first time mutations in mitochondrial transfer ribonucleic acid genes in two families with a high occurrence of preeclampsia and eclampsia. Mitochondrial dysfunction caused by point mutations of mitochondrial deoxyribonucleic acid is maternally inherited, but in the case of mutations of nuclear genes mitochondrial dysfunction can be inherited as an autosomal recessive or dominant trait.

Base Sequence↗
PubMed1968

Biochemical studies on adenovirus multiplication. 13. Synthesis of virus-specific ribonucleic acid during infection with human adenovirus type 12.

The transcription of virus-specific ribonucleic acid (RNA) was studied in KB cells infected with adenovirus type 12 (strain Huie). Viral deoxyribonucleic acid (DNA) synthesis began at 12 to 15 hr after infection, and virus maturation occurred between 20 and 50 hr after infection. The rate of incorporation of (3)H-uridine into RNA per infected cell was stimulated, reaching a maximum of 1.6 times that of uninfected cells at 20 hr after infection. "Early" viral messenger ribonucleic acid (mRNA) constituted 0.1% of RNA synthesized at 11 hr, and "late" viral mRNA constituted 50% of RNA synthesized at 45 hr after infection, as determined by hybridization of viral DNA with labeled RNA from infected cells pulse labeled with (3)H-uridine. The species of virus-specific RNA synthesized at 22 hr after infection (when virus maturation has just begun) and at 45 hr (when virus maturation is nearly complete) were studied further: (i) 22- and 45-hr RNA had the same average guanine plus cytosine content, 47%, (ii) 22- and 45-hr RNA contained mostly the same viral nucleotide sequences, (iii) 45-hr RNA had a five times higher concentration of virus-specific RNA molecules than did 22-hr RNA, and (iv) 22- and 45-hr RNA contained virus-specific nucleotide sequences transcribed from all, or nearly all, of the viral genome.

Adenoviridae↗
PubMed1991

Cellular localization of müllerian inhibiting substance messenger ribonucleic acid during human ovarian follicular development.

Müllerian inhibiting substance is expressed in the human reproductive system and has been associated with oocyte meiotic arrest. In situ hybridization was used to selectively localize ovarian cells containing high levels of müllerian inhibiting substance messenger ribonucleic acid, a müllerian inhibiting substance precursor, during different stages of human follicular development. Müllerian inhibiting substance transcript was noted in the granulosa cells of primordial, primary, and antral follicles. Surprisingly, transcript was also identified within the cytoplasm of oocytes and throughout the ovarian stroma. Controls included sense oligoprobe, positive and negative tissue controls, and treatments minus the detection antibody. Localization of transcript within the cytoplasm demonstrates that active transcription of müllerian inhibiting substance messenger ribonucleic acid occurs within both fetal and adult human female gonads. The presence of müllerian inhibiting substance messenger ribonucleic acid within oocyte cytoplasm could implicate an autocrine role for müllerian inhibiting substance-derived peptides in the establishment of oocyte competence.

Adult↗
PubMed1970

Isolation and partial characterization of Escherichia coli mutants with altered glycyl transfer ribonucleic acid synthetases.

Isolates with mutations in glyS, the structural gene for glycyl-transfer ribonucleic acid (tRNA) synthetase (GRS) in Escherichia coli, are frequently found among glycine auxotrophs. Extracts of glyS mutants have altered GRS activities. The mutants grow with normal growth rates in minimal media when high levels of glycine are provided. No other metabolite of a variety tested is capable of restoring normal growth. The glyS mutants fail to make ribonucleic acid (RNA) when depleted of exogenous glycine in strains which are RC(str) but do so when the cells are RC(rel). In contrast, biosynthetic mutants which are unable to synthesize glycine (glyA mutants) do not make RNA when deprived of glycine even if they are RC(rel); in this case, RNA is synthesized upon glycine deprivation only when the nucleic acid precursors made from glycine are provided in the medium. The level of serine transhydroxymethylase is unaltered in extracts of any of the glyS mutants, even though the level of charged tRNA(Gly) is at least 20-fold lower than that found in a prototrophic parent; this indicates that, if there is control over the synthesis of serine transhydroxymethylase, it is not modified by reduced levels of charging of the major species of tRNA(Gly).

Carbon Isotopes↗