Nature and mechanism of action of the CAMP protein of group B streptococci

Abstract

The extracellular product of group B streptococci responsible for the CAMP reaction was purified to near homogeneity. It is a relatively thermostable protein having a molecular weight of 23,500 and an isoelectric pH of 8.3. It was found that the CAMP reaction could be simulated by substituting [14C]glucose-containing liposomes prepared from sphingomyelin, cholesterol, and dicetyl phosphate for sheep erythrocytes. In the belief that the liposome system is a valid model, the mechanism of the CAMP reaction was further investigated by using liposomes in which N-acylsphingosine (ceramide) was substituted for sphingomyelin. In this system disruption of liposomes, as measured by release of trapped [14C]glucose, was effected by CAMP protein alone. As judged from thin-layer chromatography, CAMP protein caused no reduction in the amount of ceramide present in ceramide-containing liposomes, nor were split products demonstrable. However, binding of CAMP protein to ceramide-containing liposomes could be shown. It is inferred that in sheep erythrocytes CAMP protein reacts nonenzymatically with membrane ceramide formed by the prior action of staphylococcal sphingomyelinase and that binding of CAMP protein to ceramide disorganizes the lipid bilayer to an extent that results in cell lysis.

Dermatophytes can trigger cooperative (CAMP-like) haemolytic reactions

“…Bernheimer et al 15 described the principle of the mode of action of the Streptococcus agalactiae CAMP-cohaemolysin. This CAMP factor stably binds to membranes containing ceramides, e.g.…”

Biochemical and immunological characterization of the extracellular nucleases of group B streptococci.

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The emergence of the group B Streptococcus as a leading agent of neonatal sepsis and meningitis (1) has stimulated interest in furthering understanding of the biology and immunochemistry of this organism. Various antigens of the five major human group B streptococcal serotypes have been under recent investigation, including type-specific antigens (2-4) as well as an intracellular enzyme, hippuricase (5), and also the extracellular enzyme, neuraminidase (6), and CAMP protein (7). Advances in our knowledge of the group B Streptococcus have been the subject of recent reviews (8-10).Our studies were undertaken to explore the possibility that group B streptococci may elaborate extracellular nucleases different from those of group A streptococci, and that these nucleases may be valuable antigenic markers that could be used to follow the immune response to group B streptococcal colonization or infection.The frequency of production of extracellular DNase had been reported to be 38% in group B streptococci in contrast to 100% in group A streptococci (11).

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“…The emergence of the group B Streptococcus as a leading agent of neonatal sepsis and meningitis (1) has stimulated interest in furthering understanding of the biology and immunochemistry of this organism. Various antigens of the five major human group B streptococcal serotypes have been under recent investigation, including type-specific antigens (2-4) as well as an intracellular enzyme, hippuricase (5), and also the extracellular enzyme, neuraminidase (6), and CAMP protein (7). Advances in our knowledge of the group B Streptococcus have been the subject of recent reviews (8-10).…”

Molecular Characterization of Phenotypically CAMP‐Negative Streptococcus agalactiae Isolated from Bovine Mastitis

“…The test, generally considered to be highly specific for group B streptococci, is based on the detection of a diffusible extracellular protein (CAMP factor), which shows a synergistic haemolysis of sheep erythrocytes in the diffusion zone of b-toxin, a sphingomyelinase of Staphylococcus aureus. The CAMP protein was purified and further characterized by Bernheimer et al (1979) and Ju¨rgens et al (1985). The CAMP factor gene cfb of S. agalactiae has been sequenced (Podbielski et al, 1994) and differs from the comparable genes cfu of S. uberis (Jiang et al, 1996), cfa of S. pyogenes (Gase et al, 1999) and cfg of S. canis (Hassan et al, 2000).…”