Preparation and antigenicity of M protein released from group A, type 1 streptococcal cell walls by phage-associated lysin

Surface proteins of gram-positive bacteria and mechanisms of their targeting to the cell wall envelope

The cell wall envelope of gram-positive bacteria is a macromolecular, exoskeletal organelle that is assembled and turned over at designated sites. The cell wall also functions as a surface organelle that allows gram-positive pathogens to interact with their environment, in particular the tissues of the infected host. All of these functions require that surface proteins and enzymes be properly targeted to the cell wall envelope. Two basic mechanisms, cell wall sorting and targeting, have been identified. Cell well sorting is the covalent attachment of surface proteins to the peptidoglycan via a C-terminal sorting signal that contains a consensus LPXTG sequence. More than 100 proteins that possess cell wall-sorting signals, including the M proteins of Streptococcus pyogenes, protein A of Staphylococcus aureus, and several internalins of Listeria monocytogenes, have been identified. Cell wall targeting involves the noncovalent attachment of proteins to the cell surface via specialized binding domains. Several of these wall-binding domains appear to interact with secondary wall polymers that are associated with the peptidoglycan, for example teichoic acids and polysaccharides. Proteins that are targeted to the cell surface include muralytic enzymes such as autolysins, lysostaphin, and phage lytic enzymes. Other examples for targeted proteins are the surface S-layer proteins of bacilli and clostridia, as well as virulence factors required for the pathogenesis of L. monocytogenes (internalin B) and Streptococcus pneumoniae (PspA) infections. In this review we describe the mechanisms for both sorting and targeting of proteins to the envelope of gram-positive bacteria and review the functions of known surface proteins.

Studies of streptococcal cell walls. VI. Effects of adjuvants on the production of type-specific antibodies to cell walls and isolated M protein

Hayashi, James A. (University of Illinois College of Medicine, Chicago) and Gerald Walsh. Studies of streptococcal cell walls. VI. Effects of adjuvants on the production of type-specific antibodies to cell walls and isolated M protein. J. Bacteriol. 82:736-742. 1961.-Mineral oil adjuvant was shown to assist in type-specific immunization of rabbits, when use was made of isolated cell walls or pH 2-extracted M protein from type 14 group A hemolytic streptococci. The antibodies produced were type specific, and passively protected mice that were challenged with virulent type 14 streptococci. A single injection each week for 4 weeks gave good levels of antibody. Simultaneous immunization with three different types of group A streptococci resulted in production of antibodies against all three types.

Enzymatic properties of a phage-induced lysin affecting group A streptococci

Doughty, C. C. (University of Illinois College of Medicine, Chicago) and James A. Hayashi. Enzymatic properties of a phage-induced lysin affecting group A streptococci. J. Bacteriol. 83:1058-1068. 1962.-Phage-induced lysis of group C streptococci releases into the medium a lysin which completely lyses group A streptococci. Partial purification of the lytic activity yields 47% of the original activity with a 17-fold purification. The activity was assayed by observing lysis of group A streptococci under standard conditions. The optimal pH range for lysis is from 6.0 to 6.7. A monovalent cation requirement satisfied by Na(+), K(+), or Li(+) is shown by the lysin. Lysis is stimulated by ethylenedi-aminetetraacetic acid (EDTA), chlortetracycline, streptomycin, and penicillin. It is inhibited by p-hydroxymercuribenzoate (pHMB), and the inhibition is reversed by cysteine. Other inhibitors include ristocetin A and specific antisera against the lysin. Isolated group A streptococcal cell walls are partially lysed by massive amounts of lysin. This partial lysis is not affected by EDTA, pHMB, chlortetracycline, streptomycin, or ristocetin A. It is concluded that the enzymatic process of lysis of isolated cell walls is not identical to the more complex process resulting in lysis of intact cells.

FIBRINOGEN PRECIPITATION BY STREPTOCOCCAL M PROTEIN. I. IDENTITY OF THE REACTANTS, AND STOICHIOMETRY OF THE REACTION

Evidence confirming the identity of fibrinogen-precipitating factor and streptococcal M protein is provided by the demonstration of bactericidal, mouse protective, and long chain-producing antibodies in the sera of rabbits immunized with washed M-fibrinogen precipitates. Two precipitin lines were observed in immunoelectrophoresis of human plasma vs. rabbit anti-M-fibrinogen antiserum; no precipitin reactions were observed between human serum and rabbit anti-M-fibrinogen antiserum. The reaction between M protein and fibrinogen was stoichiometric; a constant equimolar ratio of reactants was observed in precipitates formed with a wide range of M protein concentrations.

ELECTROPHORETIC SEPARATION OF CONSTITUENTS OF PARTIALLY PURIFIED M PROTEIN OF STREPTOCOCCUS PYOGENES

Pierce, William A., Jr. (Tulane University, New Orleans, La.). Electrophoretic separation of constituents of partially purified M protein of Streptococcus pyogenes. J. Bacteriol. 88:912-921. 1964.-Partially purified M protein of a group A, type 12 strain of Streptococcus pyogenes was studied by use of chemical, electrophoretic, and immunological techniques. It was demonstrated in immunodiffusion tests that the antigen contains multiple precipitating components. The type-specific antigen was identified, and evidence was presented that, in some instances at least, the cross-reactions observed between this type 12 M protein and heterologous antisera in immunodiffusion tests involve contaminating antigens rather than the component which precipitates with adsorbed homologous-typing antiserum. In passive hemagglutination tests where M protein was adsorbed to tanned sheep erythrocytes, it was found that antisera suitably adsorbed to show good specificity in capillary precipitin tests nevertheless still contain cross-reactive antibodies which are detectable by this more sensitive technique. Electrophoresis on starch paste separates some of the components of partially purified M protein, so that a fraction can be obtained which has fewer precipitating antigens, as determined in immunodiffusion tests, and which is less cross-reactive in passive hemagglutination tests with heterologous unadsorbed antistreptococcal antisera.

TYPING OF GROUP A STREPTOCOCCI BY IMMUNOFLUORESCENCE. I. PREPARATION AND PROPERTIES OF TYPE I FLUORESCEIN-LABELED ANTIBODY

Karakawa, Walter W. (Connecticut State Department of Health, Hartford), Earle K. Borman, and Clarence R. McFarland. Typing of group A streptococci by immunofluorescence. I. Preparation and properties of type 1 fluorescein-labeled antibody. J. Bacteriol. 87:1377-1382. 1964.-Unadsorbed, fluorescein-labeled globulins derived from rabbits immunized with acid-extracted M-protein of type 1 streptococci (plus adjuvant) were found to have high fluorescent-antibody (FA) staining titers and to be considerably more type-specific than were similar preparations derived from whole-cell immunization. Appropriate adsorption rendered the anti-M reagent entirely type-specific without appreciable loss of titer; whole-cell reagent was appreciably weakened in FA titer by comparable adsorption. Type-specificity was confirmed by parallel bactericidal, long-chain, and precipitin studies. Removal of reactivity by adsorption with homologous M protein was complete, confirming that the FA reaction was truly a manifestation of an M anti-M protein system. The data indicate that the development of FA reagents specific for the streptococcal types is feasible.

Demonstration of protection in mice from a lethal challenge of three M serotypes of Streptococcus pyogenes using an M-negative vaccine

Mice were vaccinated with a temperature-sensitive, M-negative mutant (JC3) of Streptococcus pyogenes. This vaccine was found to offer protection from a lethal challenge of homologous M-negative and type 28 M-positive strains of S. pyogenes as well as heterologous M3 and M18 strains. Using an immunoblot method, hyperimmune serum from mice vaccinated with JC3 was found to contain moderate to high titres of antibody to all challenge strains. Additionally, this hyperimmune serum was used to probe Western blots of whole-cell proteins extracted from each of the above streptococcal strains. Three proteins were identified (M(r) = 32, 43 and 46 kDa) as immunogenic and conserved among the three serotypes studied.

Isolation and properties of a novel IgG-binding protein from streptococci of serological group U

A nonimmune binding of immunoglobulin (Ig) G has been detected in streptococci of group U. The group U Fc-binding site differed from the five previously known types of staphylococcal and streptococcal Fc-binding sites by its strong affinity for murine IgG, with dissociation constants in nanomolar range for rat and mouse IgG, as well as for mouse IgG subclasses 1, 2a, 2b and 3. It also differed from other binding sites by the high sensitivity towards trypsin. The Fc-binding protein could be solubilized from the streptococci of group U with papain and purified by gel filtration on sephacryl S-200 and by subsequent affinity chromatography on human IgG-Sepharose. The purified binding protein was homogeneous on SDS-polyacrylamide gel electrophoresis and had a molecular weight of approximately 58,000 daltons. It retained its binding activities for murine IgG subclasses as revealed by western blotting. Coupled to CNBr-activated sepharose, the purified Fc-binding protein could be effectively used for the isolation of murine IgG subclasses by affinity chromatography.

Release of Fc-receptors after streptococcal lysis induced by a lytic enzyme from Streptomyces globisporus

Streptomyces globisporus produced an enzyme which had lytic effects on streptococci and was able to solubilize their Fc-receptors. A new method for rapid purification of this enzyme was described. It consisted of adsorption to Amberlite CG 50 and subsequent chromatography on CM-cellulose Whatman CM 52. The purified enzyme was free of proteases and had lysed streptococci of serological groups A, B, C, G and L. It released Fc-receptors from the streptococcal surface in a biologically active form.

Immunochemical analysis of intact M protein secreted from cell wall-less streptococci

M protein is a major virulence factor of group A streptococci, which provides these organisms with protection against phagocytosis in the absence of specific antibody. To gain insight into the nature of the native M-protein molecule, type 12 M protein was isolated and purified from the extracellular supernatants of a group A streptococcal L form and stabilized protoplasts. The intact purified M protein from both sources had a molecular weight of 58,000, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. This is in contrast to the 32,0000-dalton molecule isolated from the parent type 12 organism by using a nonionic detergent. The purified secretory M protein removed opsonic antibodies from type 12 rabbit immune serum, as demonstrated by a bactericidal assay. Therefore, it appears that either previous nondestructive methods of M-protein isolation have not removed intact M protein from cell walls or part of the molecule is fragmented during its association with cell walls.

Purification of Streptococcus group C bacteriophage lysin

A simple procedure for the purification of Streptococcus group C phage lysin to apparent homogeneity is described. The electrophoretically pure, enzymatically stable polypeptide of 98,000 molecular weight converted Streptococcus (groups A, F, and H) cells into spheroplasts within 5 min at 0 degrees C or within less than a minute at 37 degrees C.

Immunogenicity of ribosomes from enzymatically lysed Streptococcus pyogenes

Ribosomal fractions isolated from Streptococcus pyogenes by physical and enzymatic disruption of the cell wall were found to provide protection in mice against challenge with the homologous M type. Although ribosomal fractions isolated by physical disruption of the cells also provided protection against challenge with several heterologous M types, ribosomal fractions from enzymatically lysed cells did not provide protection against any of the heterologous M types. Ribosomes isolated by either method were found to be contaminated with cell surface proteins. Chemical analysis of the ribosomes showed a greater protein:ribonucleic acid ratio in ribosomes from physically disrupted cells than in ribosomes from enzymatically disrupted cells (2:1 versus 1:1). Antisera to ribosomes isolated from physically disrupted cells detected many more antigenic determinants on ribosomes isolated from enzymatically disrupted cells than did the corresponding homologous antisera. Immunodiffusion analysis suggested that ribosomes isolated from physically disrupted cells may contain cell wall antigenic determinants which are present on ribosomes isolated from enzymatically disrupted cells in a partially degraded form. Washing of ribosomes in high-molarity salt solutions suggested that some of the contaminating cell wall proteins are tightly bound to the ribosomes.

Simple procedure for production by group C streptococci of phage-associated lysin active against group A streptococci

Phage-associated lysin of high potency was prepared by growing the host group C streptococcal strain 26RP66 in a semisynthetic medium. The lysin was stabilized by adding dithiothreitol and neutralized ethylenediaminetetraacetic acid (EDTA) to facilitate further concentration and partial purification. The lysin remained active when stored at -65 C for 1 year. Lysin was active against all strains of group A streptococci tested and was more active against living cells than heat-killed cells. The procedure outlined is practicable for most bacteriological research laboratories and does not require column purification or other complex biochemical procedures. It should be useful to any laboratory which requires small amounts of lysin to produce L-forms and protoplasts or to release streptococcal antigens.

M proteins of group A streptococci

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Studies on two methods for extraction of streptococcal T antigens

The extraction of group A streptococcal antigens by group C phage-associated lysin has been confirmed. In addition to the T antigen the extract contained M-protein, group-specific polysaccharide and mucopeptide antigen which was difficult to remove. This method of extraction of the T antigen was compared with the trypsin method. The latter method was found to be of advantage in giving a pure specific antigen.

Intergroup lysis and transduction by streptococcal bacteriophages

Bacteriophages from streptococci of groups A, E, and G lysed streptococci distributed among serogroups A, C, G, H, and L; propagated in some, but not all, of these; and transduced streptomycin resistance within group A or (by A phages only) from group A to group G streptococci.

Lysis and lysogenization of groups A, C, and G streptococci by a transducing bacteriophage induced from a group G Streptococcus

A temperate bacteriophage, designated GT-234, was isolated from a group G Streptococcus after ultraviolet irradiation. After several single-plaque passages in a group G indicator strain, this phage formed plaques in 3 of 14 group A strains, in 3 of 15 group C strains, and in 4 of 13 group G strains-but not in some representatives of several other serogroups. After propagation in each of the sensitive strains, the progeny from each was shown to be the same phage by (i) adsorption and plaque formation in each of the other groups, (ii) lysogenization in each of the other groups, (iii) high titers on infection of each serogroup, regardless of the group of propagating strain, and (iv) neutralization of infection in each of the other groups by antiserum against the phage propagated in group G. Phage GT-234 is serologically related to virulent group A phage A25, from which it is morphologically indistinguishable. Like A25, it is a transducing phage. Other studies showed that A25, as well as a group A temperate transducing phage (AT-298), could also infect strains of group C and G. These results indicate a need for reassessment of group specificity and phage receptors among streptococci of groups A, C, and G and raise possibilities for intergroup transduction.

Cell wall polysaccharide biosynthesis by membrane fragments from Streptococcus pyogenes and stabilized L-form

The formation and composition of a cell wall rhamnose-containing polysaccharide by membrane fragments from Streptococcus pyogenes and its stabilized L-form were compared. Also, the effect of prior treatment on the ability of coccal whole-cell and membrane fragments to incorporate radioactivity from thymidine diphosphate-(14)C-rhamnose, and the results of subsequent attempts to remove labeled polysaccharide from such membranes are given. L-form membrane fragments were capable of only 10% uptake of (14)C-rhamnose from this nucleotide as compared with streptococcal membranes. However, once bound, both membrane fragments polymerized rhamnose to the same extent. These findings tend to negate the almost complete lack of polymeric rhamnose within the intact L-form as being due to the absence of membrane enzymes necessary for the transfer of rhamnose from a suitable precursor to membrane acceptor sites or enzymes responsible for rhamnose polymerization. Degradation of labeled rhamnose polysaccharide after isolation from coccal membranes by mild acid hydrolysis showed muramic acid and glucosamine to be attached. This same polysaccharide from L-form membrane fragments was devoid of amino sugars. These data suggest the possible involvement of amino sugars in the attachment of cell wall polymeric rhamnose to the streptococcal cytoplasmic membrane. The absence of attached amino sugars to rhamnose polysaccharide from L-form membrane fragments is discussed in terms of this organism's continued inability for new cell wall formation. The isolation, from streptococcal membrane fragments, of a polysaccharide containing rhamnose and amino sugars common to at least two different streptococcal cell wall-type polymers was demonstrated.

Purification and physical properties of group C streptococcal phage-associated lysin

A purification procedure for the Group C phage-associated lysin is described utilizing tetrathionate to protect the enzyme's -SH group(s) from thiol-inactivating agents. A 652-fold purification has been accomplished yielding a solution in which the enzyme activity corresponds to essentially a single band on polyacrylamide gel which accounts for 70% of the total protein in the preparation. A molecular weight of 101,000 and frictional ratio of 1.526 was determined for the lysin utilizing experimentally determined values for its Stokes radius and sedimentation coefficient.

Secondary and apparent primary antibody responses after group A streptococcal vaccination of 21 children

A partially purified M protein, extracted from a mouse-virulent strain of type 3, group A streptococcus, was administered subcutaneously in gradually increasing amounts at weekly intervals to 21 children in a Family Program. Seven children with type 3 bactericidal antibody in prevaccination sera showed a secondary response. Of 14 children with no detectable type 3 bactericidal antibody prior to vaccination, 13 developed definite type 3 antibody during or soon after vaccination. This response appeared to be of the primary variety in at least some of the 13 children because (i) the total incidence of antibody response (20 of 21) was greater than can be accounted for by the documented incidence of clinical and subclinical type 3 infections among children of our Family Program during a period of 14 years, (ii) the response in the 13 children with no detectable antibody prior to vaccination was more delayed than in those showing a definite secondary response, and (iii) on the average, the amount of vaccine needed for a response in these 13 children was 15 to 28 times greater than that required for the secondary response. Local skin reactions were variable among the vaccinated children. Systemic reactions were infrequent and not severe. The giving of multiple injections of partially purified M protein did not seem to cause cutaneous hypersensitivity.

Genetic differentiation by nucleic acid homology. IV. Relationships among Lancefield groups and serotypes of streptococci

Weissman, Sherman M. (National Cancer Institute, Bethesda, Md.), Paul R. Reich, Norman L. Somerson, and Roger M. Cole. Genetic differentiation by nucleic acid homology. IV. Relationships among Lancefield groups and serotypes of streptococci. J. Bacteriol. 92:1372-1377. 1966.-A deoxyribonucleic acid-ribonucleic acid homology technique was used to measure the genetic relatedness among Lancefield groups and serotypes of streptococci. Organisms in different Lancefield groups were related, but were differentiated from each other. Serotypes within group A could be distinguished. Two isolates serologically classified in group A type 1 were indistinguishable. Streptococcus faecalis was only remotely related to streptococci of Lancefield groups A and H, whereas Diplococcus pneumoniae was more closely related to these organisms. The serological data were in good agreement with the results obtained with the homology method.

The multiple molecular structure of the M proteins of group A streptococci

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