The expression of the genes for the major outer membrane proteins OmpF and OmpC are osmoregulated. The ompC locus was found to be transcribed bidirectionally under conditions of high osmolarity and a 174-base transcript encoded upstream of ompC was found to inhibit the OmpF production and to substantially reduce the amount of the ompF mRNA. This RNA [mRNA-interfering complementary RNA (micRNA)] has a long sequence that is complementary to the 5' end region of the ompF mRNA. We propose that the micRNA inhibits the translation of the ompF mRNA by hybridizing with it. This RNA interaction may cause premature termination of the transcription of the ompF gene or destabilization of the ompF mRNA or both.

Bacterial Outer Membrane Proteins↗

PubMed1983

A comparative study on the genes for three porins of the Escherichia coli outer membrane. DNA sequence of the osmoregulated ompC gene.

The DNA sequence of the ompC gene which encodes one of the outer membrane porins has been determined. The gene appears to encode a secretory precursor of OmpC protein consisting of a total of 367 amino acid residues with a signal peptide of 21 amino acid residues at its NH2-terminal end. The 5' end noncoding region including the promoter of the ompC gene is extremely [A-T]-rich, and the codon usage in the ompC gene is unusual as are those in genes for other abundant outer membrane proteins. The promoter sequence of the ompC gene was compared with that of the ompF gene, both of which are controlled by the osmoregulatory operon, ompB. The deduced amino acid sequence of the OmpC protein showed extensive homology with that of the other porins (OmpF and PhoE proteins). The homology in the primary amino acid sequences, as well as the coding DNA sequences among the porins, indicates that the structural genes for the three porins evolved from a common ancestral gene. Comparison of the amino acid sequences among the OmpC, OmpF, and PhoE porins will be discussed with regard to structure and function.

Amino Acid Sequence↗

PubMed1983

Severe pneumococcal infection in patients with neoplastic disease.

A study of pneumococcal bacteremia in 56 patients with neoplastic disease from January 1, 1972 to June 30, 1980 is presented and compared to an earlier study between 1955 and 1971. Patients at highest risk were those with Hodgkin's disease who had been splenectomized, multiple myeloma and chronic lymphocytic leukemia showing an attack rate of 15.6/1000, 12.5/1000, and 10.8/1000, respectively. The attack rate was more than three times higher among patients with Hodgkin's disease in the present series compared to the previous series. In 32% of cases there was no identifiable source for the infection. Four splenectomized patients with Hodgkin's disease developed pneumococcal meningitis and two died. The overall mortality rate was 32% versus a rate of 18% for those treated with appropriate antibiotics for more than 24 hours. There was a significant improvement in overall survival when compared with our previous series. As before, almost one fourth (24%) of our isolates were not among those included in the pneumococcal vaccine presently available. Antibiotic prophylaxis should be considered in high risk patients.

Adolescent↗

PubMed1983

DNA sequence of the promoter region of the ompC gene and the amino acid sequence of the signal peptide of pro-OmpC protein of Escherichia coli.

The osmoregulated ompC gene of Escherichia coli was cloned and the DNA sequence of a fragment encompassing the promoter region and a portion of the coding region was determined. There were no obvious homologies in the DNA sequences of the promoter regions of the ompC and ompF genes, in contrast to those of the coding regions of the two genes, both of which code for the matrix porins (major outer membrane proteins) and form passive diffusion pores. The amino acid sequence of the signal peptide of pro-OmpC protein was also deduced from the DNA sequence.

Amino Acid Sequence↗

PubMed1982

Osmoregulation of gene expression. I. DNA sequence of the ompR gene of the ompB operon of Escherichia coli and characterization of its gene product.

The ompB region on the Escherichia coli chromosome codes for two genes, ompR and envZ, which are required for the osmolarity sensitive biosynthetic regulation of the outer membrane matrix proteins (porins), OmpF and ompC. A part of the ompB region containing the ompR gene has been cloned (Wurtzel, E. T., Movva, N. R., Ross, F. L., and Inouye, M. (1981) J. Mol. Appl. Genet. 1, 61-69). We have determined the DNA sequence, including the promoter and structural regions encompassed in a 1.3-kilobase pair Ava I-Eco RI subfragment. This fragment codes for the entire ompR gene as well as the 5' end of the envZ gene. The ompR gene codes for a protein of 32,489 daltons, consisting of 284 amino acid residues. This was confirmed by identifying the gene product by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and determining a partial amino acid sequence of the NH2-terminal region of the gene product. A sequence of 57 amino acid residues located in the COOH-terminal region of the protein is extremely basic. It contains 10 arginine plus lysine residues in contrast to 1 glutamic acid residue in this region. In vitro transcription of the DNA from this region indicates that ampR and envZ are co-transcribed as a polycistronic mRNA from a promoter located 5' to the ompR gene. Translation of the am pR gene terminates at two tandem TAS codons and translation of the envZ gene initiates 29 nucleotides downstream. Cloning of the promoter region of ompB at a site 5' to the structural portion of the beta-galactosidase gene indicates that transcription of ompB is under positive control by cAMP.

Amino Acid Sequence↗

PubMed1981

Template-specific inhibitor for DNA polymerase isolated from cauliflower inflorescence.

A novel inhibitory factor which greatly inhibits DNA polymerase activity was isolated from the apical portion of the cauliflower inflorescence during purification of DNA polymerases. It can be adsorbed on a DEAE-cellulose column, but not on CM-Sephadex or DNA-cellulose. The factor exclusively inhibits the incorporation of [3H]dTTP into DNA when poly(rA, dT10) is used as the template primer, but not when activated DNA, heat-denatured DNA or native DNA is used as a template. The concentration of the factor in the reaction medium required for 50% inhibition is approx. 8 microgram/ml. The factor is heat-stable, is inactivated by trypsin, and has a maximum ultraviolet absorption at 278 nm. The molecular weight was estimated as 2500-3000 by Sephadex gel chromatography.

Chromatography, DEAE-Cellulose↗

PubMed1980

Characterization of two DNA polymerases from cauliflower inflorescence.

Two distinct DNA polymerases, A and B, isolated from a rapidly growing apical tissue of cauliflower (Brassica oleracea var. botrytis) inflorescence have been characterized, and compared with DNA polymerases, alpha and beta, from mouse myeloma. Polymerase-A bears a strong resemblance to polymerase-alpha from mammalian cells in all properties examined. The character of polymerase-B is also quite similar to polymerase-beta of mammalian cells in chromatographic elution properties, template-primer utilization, sensitivity to inhibitors, response to KCl or KPi concentration, and other requirements for maximal activity, although it has a higher molecular weight (approx. 78,000) even in the presence of 0.25 M KCl that polymerase-beta (mol. wt. less than or equal to 50,000) of mammalian cells. This type of DNA polymerase has not been reported to exist in the plant system.

Animals↗

PubMedDate not supplied

[Staphylococcal colonization rate on neonatal nares and umbilical cord in a newborn nursery].

Staphylococcus aureus and Staphylococcus epidermidis were the most important gram positive pathogens found in a five-year study (1985-1989) of nosocomial infection in this hospital. They caused 56.2% of all nosocomial infections in this newborn nursery, particularly skin infections. To determine the reasons, and to decrease effectively the neonatal staphylococcal colonization rate, three different disinfection methods were selected for management of neonatal umbilical cords. A total of 1578 swabs from neonatal nares and umbilical cords were collected. During the first period no disinfectant was applied to the cord after bathing the baby. Beta-iodine in alcohol and bacitracin ointment were used for the second and the third periods, respectively. The result showed a significant difference (P less than 0.05) in staphylococcal colonization rate on neonatal umbilical cord using different disinfectants even after the first day. The same result for neonatal nares was also found, after infants had been in the nursery for two days. During the third period, no case of skin infection was found. Most Staphylococcus aureus isolated were resistant to ampicillin, erythromycin, tetracycline and penicillin. The percentage of this antibiogram found in neonatal nares and umbilical cords was 44% and 56% respectively. Besides nosocomial infection control and surveillance of medical personnel, environment, materials, instruments and isolation techniques, it is really necessary to choose an effective disinfectant (bacitracin ointment is recommended) to reduce the staphylococcal colonization in newborn nurseries.

Colony Count, Microbial↗

PubMedDate not supplied

[Comparison of rapid latex and conventional methods for the identification of Staphylococcus aureus].

Rapid latex agglutination assay, staphaurex (Wellcome Diagnostics) was compared with the tube coagulase, thermo-stable nuclease, deoxyribonuclease and mannitol fermentation test for the identification of Staphylococcus aureus. A total of 277 clinical isolates of Staphylococcus aureus, 201 Staphylococcus epidermidis, and 25 Staphylococcus saprophyticus were tested. The results showed that sensitivities were: staphaurex, 99.6%; rabbit plasma, 99.6%; human plasma, 99.2%; thermostable nuclease, 100%; deoxyribonuclease, 100%; mannitol fermentation, 98.9%; as for specificities results showed: staphaurex, 96.6%; rabbit plasma 100%; human plasma, 100%; thermo-stable nuclease, 98.7%; deoxyribonuclease 95.7%; mannitol fermentation, 91.1%; respectively. In our study, staphaurex is recommended because it is simple to operate, save in time and economic in cost.

Animals↗