Structural Components Of Cell Wall Research Articles

Enzymes of the yeast lytic system produced by Arthrobacter GJM‐1 bacterium and their role in the lysis of yeast cell walls

AbstractYeast lytic system produced by Arthrobacter GJM‐1 bacterium during growth on baker's yeast cell walls contains a complete set of enzymes which can hydrolyze all structural components of cell walls of Saccharomyces cerevisiae. Chromatographic fractionation of the lytic system showed the presence of two types of endo‐ß‐1,3‐glucanase. Rapid lysis of isolated cell walls of yeast was induced only by endo‐ß‐1,3‐glucanase exhibiting high affinity to insoluble ß‐1,3‐glucans and releasing laminaripentaose as the main product of hydrolysis of ß‐1,3‐glucans. This enzyme was able to lyse intact cells of S. cerevisiae only in the presence of an additional factor present in the Arthrobacter GJM‐1 lytic system, which was identified as an alkaline protease. This enzyme possesses the lowest molecular weight among other identified enzyme components present in the lytic system. Its role in the solubilization of yeast cell walls from the outer surface by endo‐ß‐1,3‐glucanase could be substituted by preincubation of cells with Pronase or by allowing the glucanase to act on cells in the presence of thiol reagents. The mechanism of lysis of intact cells and isolated cell walls by the enzymes of Arthrobacter GJM‐1 is discussed in the light of the present conception of yeast cell wall structure.

Phenotypes of pleiotropic-negative sporulation mutants of Bacillus subtilis.

The phenotypic properties of representatives of the five genetic classes of pleiotropic-negative sporulation mutants have been investigated. Protease production, alkaline and neutral proteases, was curtailed in spoA mutants, but the remainder of mutant classes produced both proteases, albeit at reduced levels. The spoA and spoB mutants plaqued phi2 and phi15 at high efficiency, but the efficiency of plating of these phages on spoE, spoF, and spoH mutants was drastically reduced. Antibiotic was produced by the spoH mutants and to a degree by some spoF mutants, but the other classes did not produce detectable activity. The spoA mutants were less responsive to catabolite repression of histidase synthesis by glucose than was the wild type. Severe catabolite repression could be induced in spoA mutants by amino acid limitation, suggesting that the relaxation of catabolite repression observed is not due to a defect in the mechanism of catabolite repression. Although others have shown a perturbation in cytochrome regulation in spoA and spoB mutants, the primary dehydrogenases, succinate dehydrogenase and reduced nicotinamide adenine dinucleotide dehydrogenase, leading to these cytochromes are unimpaired in all mutant classes. A comparison of the structural components of cell walls and membranes of spoA and the wild type is made. The pleiotropic phenotypes of these mutants are discussed.

Influence of Photoperiod and Thermoperiod on the IVDMD and Cell Wall Components of Tall Fescue1

‘Kenwell’ and ‘Kentucky 31’ tall fescue (Festuca arundinacea Schreb.) were grown in chambers under the following conditions: (a) 27/16 C day/night temperature, 16‐hour photoperiod, (b) 27/16 C day/night temperature, 10‐hour photoperiod, (c) 16/4 C day/night temperature, 16‐hour photoperiod, and (d) 16/4 C day/night temperature, 10‐hour photoperiod. Two harvests were taken. Both long days and high temperatures significantly (P<0.01) lowered the percent in vitro dry matter digestibility (IVDMD) and also lowered the percent in vitro cellulose digestibility of tall fescue. These changes in digestibility were associated with increased levels of structural cell wall components. In the second harvest Kenwell was significantly greater in percent IVDMD (P<0.01) and hemicellulose (P<0.05) than Kentucky 31.

Polyuronides as structural components of cell walls of fungi and green algae.

X-RAY diffraction studies of the products of the cell walls of yeasts and hyphal fungi have revealed several new components in the latter1, including an unknown product in the mycelial walls of Phycomyces blakesleeanus. This was revealed by its diffraction rings, which, together with those of chitin, were present in X-ray diagrams of walls treated with boiling 2 per cent HCl (Fig, 1a). The product was soluble in warm dilute alkali, could be reprecipitated by acidifying and was also isolated in a different manner1. It then produced an X-ray diagram similar to that in Fig. 1b, with four diffraction rings corresponding to the spacings in the first column of Table 1. Fig. 1b actually shows the diffraction pattern of the same product obtained from acid-treated walls of the fibrous exoperidium layer of a species of Geaster. The same diffraction lines could also be distinguished among those of chitin in the residue left after the walls of the yeast Sporobolomyces roseus had been treated with acid. This wall component is evidently widely distributed among different groups of fungi.

Quantitative Analysis of Actinomyces Cell Walls

Quantitative data on the amino acid composition of cell walls of five species of Actinomyces were obtained by using a Beckman-Spinco amino acid analyzer. The major amino acids in A. israelii, A. naeslundii, A. eriksonii , and A. bovis species included alanine, glutamic acid, lysine, aspartic acid, and ornithine, as reported by previous workers, whereas A. propionicus contained diaminopimelic acid. Other amino acids, including glycine, valine, leucine, proline, isoleucine, and threonine, were present in at least some of the walls in quantities equal to or slightly less than that of lysine. This raised the question of whether these may represent cross-links in the peptidoglycan or other cell wall structural components or whether the wall preparations contained nonpeptidoglycan material despite the use of electron microscopy as a standard of purity; further work is required to supply the answer. The quantitative data furnish relative molar concentrations of amino acids, which can provide definitive identification of some of the species and differentiation of Actinomyces from other members of the Actinomycetales and from morphologically similar genera such as Corynebacterium and Propionibacterium .

Quantitative Analysis of Actinomyces Cell Walls

Quantitative data on the amino acid composition of cell walls of five species of Actinomyces were obtained by using a Beckman-Spinco amino acid analyzer. The major amino acids in A. israelii, A. naeslundii, A. eriksonii, and A. bovis species included alanine, glutamic acid, lysine, aspartic acid, and ornithine, as reported by previous workers, whereas A. propionicus contained diaminopimelic acid. Other amino acids, including glycine, valine, leucine, proline, isoleucine, and threonine, were present in at least some of the walls in quantities equal to or slightly less than that of lysine. This raised the question of whether these may represent cross-links in the peptidoglycan or other cell wall structural components or whether the wall preparations contained nonpeptidoglycan material despite the use of electron microscopy as a standard of purity; further work is required to supply the answer. The quantitative data furnish relative molar concentrations of amino acids, which can provide definitive identification of some of the species and differentiation of Actinomyces from other members of the Actinomycetales and from morphologically similar genera such as Corynebacterium and Propionibacterium.