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At least 19 recordsLinked to original sources
PubMed1974

Specificity of the autolysin of Streptococcus (Diplococcus) pneumoniae.

A Streptococcus (Diplococcus) pneumoniae autolysin, partially purified from cellular autolysates, was optimally active at pH 7.0 and was stimulated by monovalent cations. Addition of autolysin to walls resulted in the appearance of only N-terminal l-alanine, whereas no glycosidase activity was observed. Walls which had been solubilized by autolysin were separated by gel filtration into a low-molecular-weight peptide containing amino acids in the same ratios found in intact walls and a high molecular fraction containing the amino acid-deficient peptidoglycan backbone. Thus, the major activity is an N-acetylmuramyl-l-alanine amidase. In addition, walls undergoing spontaneous lysis revealed no glycosidase activity but showed an increase in only N-terminal alanine. Autolysin, which was bound to walls in saline, was almost completely removed when walls were washed in distilled water, and all of the activity was recovered in the water wash fluid.

Alanine↗
PubMed1973

Competence for deoxyribonucleic acid uptake and deoxyribonuclease action external to cells in the genetic transformation of Diplococcus pneumoniae.

A mutant of Diplococcus pneumoniae that apparently does not require activator can become competent for uptake of deoxyribonucleic acid (DNA) when grown in dilute cultures or in the presence of trypsin. Development of competence in both mutant and wild strains is temperature dependent, being 10-fold greater at 30 C than at 37 C. Induction of competence on a shift from 37 to 30 C requires protein synthesis and the presence of Mg(2+) and Ca(2+); uptake of DNA does not require protein synthesis. Competence decays exponentially at higher temperatures. As well as taking up DNA, competent cells release oligonucleotide fragments of donor DNA in the medium external to the cells. Normal strains release fragments comparable in amount to the DNA taken up; but, in a mutant selected for inability to degrade DNA in agar, the amount of fragments formed external to the cells is only 40% of DNA uptake. Requirements for external deoxyribonuclease action are identical to those for DNA uptake: prior development of competence and the presence during treatment with DNA of Mg(2+) ions and a source of energy.

Calcium↗
PubMed1975

Identification of a deoxyribonuclease implicated in genetic transformation of Diplococcus pneumoniae.

A mutation of Diplococcus pneumoniae, end-1, reduces the major deoxyribonuclease activity of the cell, an endonuclease, to 10% of its normal value without impairing transformation. Further mutations, called noz, abolish the residual endonuclease activity and block transformation. The residual endonuclease is similar to the wild-type enzyme in size, charge, divalent cation dependence, inhibition by ribonucleic acid, and formation of oligonucleotide products. However, the mutant endonuclease is more temperature sensitive, which suggests that the end-1 mutation occurred in a structural gene for the enzyme. Genetic analysis showed that the noz mutations occur at the same genetic locus. A number of new end mutants were analyzed. Those that retained more than 1.4% of the normal endonuclease activity were essentially normal in transformation; those with less than 1% were defective. The transformation-defective end mutants appear to be blocked in the entry of deoxyribonucleic acid (DNA) since they carry out the prior step of binding DNA to the outside of the cell. The major endonuclease of the cell may act as a DNA translocase by attacking and degrading one strand of DNA, thereby facilitating entry of the complementary strand into the cell.

Cations, Divalent↗
PubMed1964

THE FINE STRUCTURE OF DIPLOCOCCUS PNEUMONIAE.

The fine structure of an unencapsulated strain of Diplococcus pneumoniae is described. A striking feature of these bacteria is an intracytoplasmic membrane system which appears to be an extension of septa of dividing bacteria. The possible function of these structures and their relationship to the plasma membrane and other types of intracytoplasmic membranes found in pneumococcus is discussed.

Bacteria↗
PubMed1962

Population changes in Diplococcus pneumoniae.

Carta, G. (Wesleyan University, Middletown, Conn.) and W. Firshein. Population changes in Diplococcus pneumoniae. J. Bacteriol. 84:473-477. 1962.-Avirulent mutant strains derived from pneumococcal types I, II, III, and VII established themselves in initially virulent or predominantly virulent populations within 36 to 48 hr of incubation at 37 C in Brain Heart Infusion-blood broth. Aged blood-broth cultures or broth cultures lacking blood permitted a more rapid establishment of avirulent cells. This selective population change was due to a greater viability of avirulent than virulent cells, in the stationary phase, and to a toxic factor, produced by large numbers of avirulent cells, which inhibited the multiplication of virulent cells. Virulent cultures were stabilized, however, by the addition of mixtures of deoxynucleosides and deoxynucleotides, which prevented the establishment of avirulent cells.

Culture Media↗
PubMed1976

Partial purification and characterization of an endo-alpha-N-acetylgalactosaminidase from the culture of medium of Diplococcus pneumoniae.

The culture medium of Diplococcus pneumoniae contains enzymic activity that cleaves Galbeta1 leads to 3GalNAc from desialized human erythrocyte membrane glycoprotein. The enzyme was purified 180-fold by ammonium sulfate fractionation, gel filtration through a Sephadex G-200 column, and DEAE A-25 Sephadex chromatography. The purified enzyme liberates Galbeta1 leads to 3GalNAc from glycopeptides and glycoproteins with Galbeta1 leads to 3GalNAcalpha1 leads to Ser and Thr moieties. The optimum pH of this enzyme is 6.0. Using glycopeptides obtained by trypsin digestion of human erythrocyte membrane glycoprotein as a substrate, a Km of 0.20 mM (on the basis of the amount of Galbeta1 leads to 3GalNAc residues) was obtained. So far, the enzyme appears to have a strict specificity for Galbeta1 leads to 3GalNAcalpha1 leads to Ser and Thr structures, because no oligosaccharides larger than trisaccharides were liberated from porcine submaxillary mucin.

Cations, Divalent↗
PubMed1963

FOLIC ACID DERIVATIVES SYNTHESIZED DURING GROWTH OF DIPLOCOCCUS PNEUMONIA.

Sirotnak, F. M. (Sloan-Kettering Institute for Cancer Research, New York, N.Y.), Gloria J. Donati, and Dorris J. Hutchison. Folic acid derivatives synthesized during growth of Diplococcus pneumoniae. J. Bacteriol. 85:658-665. 1963.-Under cultural conditions permitting synthesis of folic acid in an amount greatly in excess (20- to 30-fold) of that required for maximal growth of Diplococcus pneumoniae, 85 to 90% of the growth factor accumulated as polyglutamates. Approximately equal amounts of mono- and diglutamates made up the remaining 10 to 15% found in culture material. Most of the polyglutamates occurred intracellularly, in a proportion of triglutamates to higher glutamates of about two to one. Only 10 to 15% of all folic acid derivatives (mono-, di-, and polyglutamates) found had folinic acid (5-formylfolate-H(4)) activity for Pediococcus cerevisiae. Practically all synthesis of the glutamyl-peptide moieties of folate seems to occur at an enzymatic step prior to folic acid, since no appreciable peptide formation occurred under conditions blocking folate synthesis. Sulfanilamide inhibition of growth by a block in folate synthesis was reversed by the addition of dihydrofolic acid, but not folic acid. The examination of two genetically distinct amethopterin-resistant mutant strains has revealed no gross differences in folate accumulation during growth when compared with the wild strain.

Antimetabolites↗
PubMed1963

ALTERATION IN TRANSFORMABILITY OF DIPLOCOCCUS PNEUMONIAE AFTER THE ACQUISITION OF GENETIC DETERMINANTS INDUCING RESISTANCE TO ERYTHROMYCIN.

Sirotnak, Francis M. (Sloan-Kettering Institute for Cancer Research, New York, N.Y.), Ramona B. Lunt, and Dorris J. Hutchison. Alteration in transformability of Diplococcus pneumoniae after the acquisition of genetic determinants inducing resistance to erythromycin. J. Bacteriol. 86:735-739. 1963.-The genetic alteration of a highly transformable (competent) recipient strain of Diplococcus pneumoniae by the transformation of at least two of three identified erythromycin-resistance determinants (Ery(a), Ery(b), Ery(c)) results in a marked decrease (Ery(a-b) recombinant) or complete loss (Ery(a-c) recombinant) in the ability to be transformed. The occurrence of transformable cells in cultures of the R6 Ery(a-b) recombinant strains, although greatly diminished, still varies during growth in a manner characteristic of the fully competent parent strain. Both Ery(b) and Ery(c) determinants appear to be linked to Ery(a). In experiments using P(32)-labeled deoxyribonucleic acid (DNA), data correlating DNA uptake with transformation show a decrease or loss in uptake capacity of the erythromycin-resistant strains.

DNA↗
PubMed1974

Bacterial growth in vivo. An important determinant of the pulmonary clearance of Diplococcus pneumoniae in rats.

Lung clearance of Diplococcus pneumoniae was markedly reduced in rats with acute hemorrhagic pulmonary edema produced by instillation of hydrochloric acid. Bacterial clearance was enhanced in both control and acid-instilled animals by pretreatment with a bacteriostatic antibiotic, tetracycline, 30 mg/kg. From these data the contributions of bacterial multiplication and bacterial elimination to net lung bacterial clearance were estimated. In control animals the constant for exponential bacterial elimination was -1.4283 (fractional clearance = 76% per h), and the doubling time for the pneumococcus was 170 min. In acid-instilled rats the elimination constant was -0.5336 (fractional clearance = 41% per h), and the doubling time of the pneumococcus was 47 min, approximating the doubling time of 42 min observed with pneumococci grown in broth. These results indicate that, in the case of pneumococci, both bacterial elimination and bacterial growth contribute to lung bacterial clearance in normal animals as well as animals with damaged lungs. In the present study changes in both parameters were required to explain the observed results in acid-instilled animals. The pulmonary pathogenicity of some bacterial species may be determined by their capacity for growth in the lung, since infection of the lung occurs when bacterial multiplication exceeds the rate of elimination of viable organisms.

Aerosols↗
PubMed1975

Membrane location of a deoxyribonuclease implicated in the genetic transformation of Diplococcus pneumoniae.

The cellular localization of enzymes in Diplococcus pneumoniae was examined by fractionation of spheroplasts. A deoxyribonuclease implicated in the entry of deoxyribonucleic acid (DNA) into the cell during genetic transformation was located in the cell membrane. This enzyme, the major endonuclease of the cell (endonuclease I), which is necessary for the conversion of donor DNA to single strands inside the cell and oligonucleotides outside, thus could act at the cell surface. Another enzyme, the cell wall lysin (autolysin), was also found in the membrane fraction. Other enzymes, including amylomaltase, two exonucleases, and adenosine triphosphate-dependent deoxyribonuclease, and a restriction type endonuclease, were located in the cytosol within the cell. None of the enzymes examined were predominantly periplasmic in location. Spheroplasts were obtained spontaneously on incubation of pneumococcal cells in concentrated sugar solutions. The autolytic enzyme appears to be involved in this process. Cells that were physiologically competent to take up DNA formed osmotically sensitive spheroplasts two to three times faster than cells that were not in the competent state. Although some genetically incompetent mutants also formed spheroplasts more slowly, other such mutants formed them at the faster rate.

Cell Fractionation↗