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At least 163 records · Page 9Linked to original sources
PubMed1994

Phage-associated differences in staphylococcal enterotoxin A gene (sea) expression correlate with sea allele class.

Staphylococcus aureus strains which produced either high or low levels of staphylococcal enterotoxin A (SEA) with a minimal eightfold difference between the two groups were identified. For FRI100 and FRI281A (prototypes for each group), strain differences in the expression of the SEA-encoding gene (sea) were found to occur at the level of sea mRNA concentration, and part of the difference in expression was associated with the sea-containing phages. Southern blot analysis revealed that this phage-associated difference was not due to differences in the copy number of sea. Nucleotide sequence analysis of sea from FRI281A revealed a new allele of sea, with the majority of the sequence differences occurring in the upstream promoter region. Although a strict correlation was observed between the level of SEA production and sea allele class for several strains, the sequence differences observed in the upstream region were not sufficient in themselves to alter the expression level of sea.

Alleles↗
PubMed1957

Staphylococcal virolysin, a phage-induced lysin; its differentiation from the autolysis of normal cells.

Virolysin is a lysin which appears in Staphylococcus aureus K(1) cells infected with phage P(14); together with phage, virolysin is released from phage-infected cells at the time of lysis. Autolysin is a lysin formed by uninfected cells of the K(1) strain; autolysin is released from uninfected cells by autolysis. They show the following similarities: Both agents act within the genus Micrococcus. They lyse cells only after the cell has been subjected to a damaging or "sensitizing" treatment, such as heat, bacteriophage, acetone, or ultraviolet irradiation. The course of lysis of heated cells by both lysins has been found to proceed in a similar manner. A constant percentage of cells is lysed, independent of the concentration of lysin; the residual cells remain resistant to either lysin. Lysis proceeds logarithmically with time, and the velocity constants K are proportional to the lysin concentration. K increases with increasing temperature. Both lysins are unaffected by antiserum to the phage. They are inhibited alike by a number of chemicals, including known enzyme inhibitors. Both agents are destroyed by proteolytic enzymes and are precipitated by 40 per cent saturation with (NH(4))(2)SO(4). Both lysins are very thermolabile. The two lysins differ with respect to their pH optimum, antigenic relationship and specificity for Micrococcus lysodeikticus. These results suggest that (1) both lysins have many properties associated with enzymes, (2) the lysis of heated cells, which they produce, has some of the characteristics of a chemical reaction, (3) the lysin from the phage-infected cell is clearly different from the lysin of the uninfected cell.

Autolysis↗
PubMed1974

New type of exfoliatin obtained from staphylococcal strains, belonging to phage groups other than group II, isolated from patients with impetigo and Ritter's disease.

Four strains of Staphylococcus aureus of a phage type other than the second group, isolated from patients with impetigo and Ritter's disease, were found to produce an exotoxin similar to those reported by Melish et al. (1972), Kapral and Miller (1971), and Arbuthnott et al. (1973). This toxin could elicit a general exfoliation of the epidermis with the so-called Nikolsky sign when subcutaneously inoculated into neonatal mice within 4 days after birth. The new toxin was serologically different from exfoliatin produced by the phage group II staphylococci previously reported (Kondo et al., 1973) and showed an electrophoretic pattern corresponding to that of the B-type toxin of the latter in acrylamide disc electrophoresis. It had the same molecular weight as that of the latter, which was estimated to be about 24,000. It was thermolabile and lost its toxic activity by heating at 60 C for 30 min; in addition, most of the toxicity was lost within 1 month of storage even at -30 C. We propose to designate the old typical heat-stable exfoliatin as S. aureus exfoliatin A and the new heat-susceptible exfoliatin as S. aureus exfoliatin B.

Animals↗
PubMed1980

Localization of bacteriophage receptor, clumping factor, and protein A on the cell surface of Staphylococcus aureus.

The surface of several laboratory strains of Staphylococcus aureus were observed with a scanning electron microscope, and the presence of two morphologically characteristic structures--a ridge separating cell surface into old and new surfaces and a concentric circular structure--are described. These two structures seemed to be present universally on the surfaces of cells of the genus Staphylococcus. The removal of the circular structures by a mild treatment of the cell with trichloroacetic acid suggested that this structure seemed to represent circularly arranged teichoic acid. With experiments using morphologically recognizable markers among three of the cell wall components, clumping factor, phage receptor, and protein A, the clumping factor was proven to be specifically localized on the old surface; and more phage receptors were detected on the old surface than on the new surface, but protein A was present all over the cell surface. This indicated that the clumping factor and most of the phage receptors appeared on the cell wall surface in a late stage of the cell growth cycle, but protein A was present in an early stage of the growth. The idea of aging of the cell wall is discussed.

Agglutinins↗