PURIFICATION OF STAPHYLOCOCCAL BETA-HEMOLYSIN AND ITS ACTION ON STAPHYLOCOCCAL AND STREPTOCOCCAL CELL WALLS

Inhibiting bacterial toxins by channel blockage

Emergent rational drug design techniques explore individual properties of target biomolecules, small and macromolecule drug candidates, and the physical forces governing their interactions. In this minireview, we focus on the single-molecule biophysical studies of channel-forming bacterial toxins that suggest new approaches for their inhibition. We discuss several examples of blockage of bacterial pore-forming and AB-type toxins by the tailor-made compounds. In the concluding remarks, the most effective rationally designed pore-blocking antitoxins are compared with the small-molecule inhibitors of ion-selective channels of neurophysiology.

Purification and properties of staphylococcal delta hemolysin

Large amounts (200 mg per liter of culture supernatant fluid) of highly purified staphylococcal soluble delta hemolysin were obtained by adsorption to and selective elution from hydroxyapatite followed by exhaustive dialysis against water, concentration by polyvinylpyrrolidone or polyethylene glycol 20,000 dialysis, and a final water dialysis. No carbohydrate, phosphorus, or inactive 280-nm absorbing material was detected in the preparation; however, analysis by density gradient centrifugation, gel filtration, analytical ultracentrifugation, carboxymethyl cellulose chromatography, polyacrylamide disc gel electrophoresis, isoelectric focusing, and electron microscopy revealed that the lysin was molecularly heterogeneous. The preparation contained an acidic fibrous lysin (S(20,w) of 11.9) and a basic lysin component composed of a population of granular aggregates of various sizes, with a maximum S(20,w) of approximately 4.9. No other staphylococcal products were detected in the preparation. The lysin was active against erythrocytes from many animal species and acted synergistically with staphylococcal beta hemolysin against sheep erythrocytes. It was soluble in chloroform-methanol (2:1), was inactivated by various phospholipids, normal sera, and proteolytic enzymes, but was partially resistant to heat inactivation. Activity was not affected by Ca(2+), Mg(2+), citrate, ethylenediaminetetraacetic acid, or cysteine. The lysin preparation also disrupted bacterial protoplasts and spheroplasts, erythrocyte membranes, lysosomes, and lipid spherules, was growth-inhibitory for certain bacteria, and clarified egg yolk-agar. Large amounts produced dermonecrosis in rabbits and guinea pigs. The minimum lethal intravenous dose for mice and guinea pigs was approximately 110 and 30 mg/kg, respectively.

Plasmid-mediated production of staphylococcin in bacteriophage type 71 Staphylococcus aureus

Staphylococcin production by Staphylococcus aureus strain C55 was eliminated when producing strains were exposed to various curing treatments. Acridine orange, ethidium bromide, and sodium dodecyl sulfate each effected less than 15% cure rates in treated cells. Rifampin eliminated the staphylococcin in 83% of treated isolates, and growth at 42 C resulted in a 97% cure rate. Curing of staphylococcin production and elimination of penicillinase plasmid were independent of one another. Several characteristics of the cured strains were examined and compared with the bacteriocin-producing strains. Whereas bacteriocin-producing cells were resistant to the bactericidal action of the staphylococcin and failed to adsorb it, cured cells adsorbed the staphylococcin and were susceptible to its lethal effect.

Antibody responses in sheep vaccinated against Staphylococcus aureus mastitis: a comparison of two experimental vaccines containing different adjuvants

A double-blind, placebo-controlled study was conducted to compare two vaccines using different adjuvants with regard to their ability to stimulate antibody production against the alpha- and beta-toxins and the exopolysaccharide of Staphylococcus aureus. The vaccines contained identical antigens, consisting of inactivated whole bacteria of two strains of S. aureus in addition to alpha- and beta-toxoid. One vaccine contained mineral oil, while the other used a water-soluble acrylic acid polymer resin (Carbopol) as adjuvant. Saline served as the placebo. One hundred and forty ewes were vaccinated twice before lambing, by subcutaneous injection with vaccine or placebo in the region of the supramammary lymph node, and were observed and sampled over a period of 6 months. The vaccine containing mineral oil as adjuvant induced significantly greater immune responses to the alpha- and beta-toxins than did the vaccine containing Carbopol. The latter vaccine induced higher levels of antibodies to exopolysaccharide. The degree of local adverse reactions did not differ between the two groups. The results indicate differences between the oil-adjuvanted and Carbopol-adjuvanted vaccines with regard to their ability to stimulate antibody production against S. aureus protein antigens in sheep.

Cloning and expression in Escherichia coli and Staphylococcus aureus of the beta-lysin determinant from Staphylococcus aureus: evidence that bacteriophage conversion of beta-lysin activity is caused by insertional inactivation of the beta-lysin determinant

The beta-lysin determinant (Hlb) from Staphylococcus aureus CN6708 was cloned in Escherichia coli K-12 using the bacteriophage replacement vector lambda L47.1. The Hlb determinant was localised to a 1250 base pair DNA sequence by cloning fragments from a Hlb+ recombinant phage into the plasmid vectors pACYC184 and pBR322 in E. coli K-12, and by the subsequent construction and analysis of several sub-clones, in vitro deletion and Tn5 insertion mutations. E. coli cells harbouring Hlb+ plasmids expressed readily detectable levels of beta-lysin and sphingomyelinase activity, which were located in the cytoplasm. Two polypeptides of molecular weight 38,000 and 33,000 which were encoded by the Hlb determinant were detected in E. coli minicells, but only the 33,000 dalton protein was detected in immunoblotting experiments with specific anti-beta-lysin serum. Hybridisation analysis with probes made from the cloned Hlb determinant and from DNA of the staphylokinase-converting phage phi 13, indicated that bacteriophage conversion of S. aureus to loss of beta-lysin activity is due to insertion of phi 13 DNA into or adjacent to the beta-lysin determinant. A shuttle plasmid was used to transfer the cloned Hlb determinant into a beta-lysin negative strain of S. aureus where the wild-type chromosomal determinant was inactivated by lysogenic conversion. Beta-lysin activity was readily detected in supernatants of S. aureus harbouring the cloned determinant.

Effects of metal ions on sphingomyelinase activity of Bacillus cereus

Some divalent metal ions were examined for their effects on sphingomyelinase activity of Bacillus cereus. The enzyme activity toward mixed micelles of sphingomyelin and Triton X-100 proved to be stimulated by Co2+ and Mn2+, as well as by Mg2+. Km's for Co2+ and Mn2+ were 7.4 and 1.7 microM, respectively, being smaller than the Km for Mg2+ (38 microM). Sr2+ proved to be a competitive inhibitor against Mg2+, with a Ki value of 1 mM. Zn2+ completely abolished the enzyme activity at concentrations above 0.5 mM. The concentration of Zn2+ causing 50% inhibition of the enzyme activity was 2.5 microM. Inhibition by Zn2+ was not restored by increasing concentrations of Mg2+ when the concentration of Zn2+ was above 10 microM. Ba2+ was without effect. When sphingomyelinase was incubated with unsealed ghosts of bovine erythrocytes at 37 degrees C, the enzyme was significantly adsorbed onto the membrane in the presence of Mn2+, Co2+, Sr2+ or Ba2+. Incubation with intact or Pronase-treated erythrocytes caused enzyme adsorption only in the presence of Mn2+. In the course of incubation, the enzyme was first adsorbed on the membranes of intact bovine erythrocytes in the presence of Mn2+; then sphingomyelin breakdown proceeded with ensuing desorption of adsorbed enzyme. Hot-cold hemolysis occurred in parallel with sphingomyelin breakdown. In this case, the hydrolysis of membranous sphingomyelin as well as the initial enzyme adsorption took place in the following order: unsealed ghosts greater than Pronase-treated erythrocytes greater than intact erythrocytes.

The hemolysins of Staphylococcus aureus

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Purification and characterization of thermostable direct hemolysin of Vibrio parahaemolyticus

A thermostable direct hemolysin was purified from culture filtrates of Vibrio parahaemolyticus. The purified hemolysin gave one precipitation line with the antihemolysin antiserum on agar-gel diffusion test and a single band on polyacrylamide gel electrophoresis. The hemolysin was not inactivated by heating at 70 to 100 C for 10 min. The hemolytic activity was not enhanced by the addition of lecithin. It was demonstrated that the hemolysin was a protein with a molecular weight of approximately 118,000. Amino acid analysis revealed that 43% of total amino acids were acidic amino acids, whereas 11% were basic amino acids.

Beta hemolysin: a persistent impurity in preparations of staphylococcal nuclease and enterotoxin

Purified staphylococcal nuclease and enterotoxin B from several sources contained beta hemolysin whose physicochemical resemblances to the other two proteins make its elimination difficult.

Bactericidal substance from Staphylococcus aureus. Biological properties

A bactericidal substance previously isolated from phage type 71 Slaphylococcus aureus has been further identified and characterized. Staphylococci belonging to phage type 71 produce the substance in higher titers than staphylococci lysed by other phages in group II in addition to phage 71. Other staphylococci do not produce the bactericidal substance. The bactericidal substance shares several of the properties of bacteriocins but differs from this group of antibiotic substances in some respects. A combination of ammonium sulfate fractionation and gel filtration on a Sephadex G-100 column resulted in considerable degree of purification of the bactericidal substance. The substance is a previously unrecognized product of S. aureus and is distinct from other extracellular products of this organism.

Purification and properties of staphylococcal beta hemolysin. II. Purification of beta hemolysin

Staphylococcal beta hemolysin from the 681 strain of Staphylococcus aureus grown in a Heart Infusion dialysate semisolid medium under 10% carbon dioxide was obtained in an immunoelectrophoretically pure form by a combination of procedures of precipitation with 2 volumes of acetone followed by chromatography on diethylaminoethyl cellulose at pH 6.0. The acetone precipitation procedure did not show any deleterious effect on the hemolytic activity of the beta hemolysin unless the precipitate was left in contact with the acetone for at least 4 hr. The crude preparations contained two types of beta hemolysin. One of these represented the major portion of the total activity of beta hemolysin and behaved as a cation. The other represented a minor (1/5,000) portion of the total beta hemolysin activity and behaved as an anion. These active principles were designated as cationic and anionic beta hemolysins, respectively. An unexpected increase in the total beta hemolysin activity of the crude preparations was noted when these were concentrated by dialysis against polyethylene glycol (20 m). This effect was probably due to polyethylene glycol. A further unexpected increase in the titer of the acetone-precipitated preparations occurred when these were lyophilized. The reason for this incremental increase is not known. It may be due to fragmentation of the beta hemolysin.

Enzymatic detection of the growth of Staphylococcus aureus in foods

A specific method has been developed for the extraction and measurement of staphylococcal nuclease in foods in which Staphylococcus aureus has grown. The method was used to compare staphylococcal growth with nuclease production in foods under varying conditions of temperature, aerobiosis, and competition from other microorganisms. It was concluded that the nuclease is produced under any conditions that permit growth of S. aureus, and little or no interference with the test was encountered either from mixed, natural populations or from a variety of pure, laboratory cultures. Nuclease and enterotoxin A production were shown to vary in synchrony for the 234 (Casman) strain of S. aureus, and the sensitivity of the enzymatic detection of nuclease was comparable to the sensitivity of serological detection of enterotoxin A. It was found that 15 min at 121 C was required to reduce the nuclease activity in slurries of contaminated ham below the level present in the unheated slurry. The extraordinary heat resistance of the nuclease permits its detection even in foods heated subsequent to the growth of S. aureus. The nuclease analysis requires about 3 hr to complete and requires no unusual equipment or reagents.

Saphylococcal beta-hemolysin. I. Purification of beta-hemolysin

The purification of staphylococcal beta-hemolysin was accomplished by the successive use of three protein fractionation methods. The first method employed was a double precipitation with the use of ammonium sulfate at 65% saturation. The second phase of purification used Sephadex G-100 column fractionation. The third phase utilized either carboxymethyl cellulose or diethylaminoethyl cellulose fractionation. The last two fractionation methods both resulted in the separation of a relatively high concentration of cationic hot-cold lysin and a low concentration of anionic hot-cold lysin. Because of the low concentration of the anionic component, its purity could not be assessed. However, the purity of the cationic component was demonstrated by immunodiffusion, microimmunoelectrophoresis, and by disc polyacrylamide gel electrophoresis. In addition, antisera against purified cationic beta-hemolysin yielded one line of precipitate when tested against the original crude beta-hemolysin. The purified cationic beta-hemolysin was stable in the lyophilized state. Crude beta-hemolysin was dermonecrotic, whereas purified cationic beta-hemolysin was not dermonecrotic even after Mg(++) activation.

The nature of staphylococcal beta hemolysin. I. Mode of action

The mode of action of highly punned beta hemolysin derived from the R-1 strain of Staphylococcus aureus has been investigated. Sphingomyelin was absent from lipid extracts of sheep erythrocytes treated with beta hemolysin when compared to normal cells. A correlation was also established between the sphingomyelin content of other erythrocyte species and their sensitivity to beta hemolysin. Further investigations revealed that sphingomyelin is hydrolyzed to yield phosphorylcholine and N-acyl sphingosine. Thus, the mode of action of the beta hemolysin is like that of phospholipase C. Various phosphate compounds other than sphingomyelin, including RNA, glycerophosphate, phenyl-phosphate, phosphatidylethanolamine, and phosphatidylcholine were tested as substrates, but virtually no hydrolysis was observed. In contrast with the results of other workers, R-1 beta hemolysin did not release detectable amounts of carbohydrate from staphylococcal cell walls.