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C Panos

Publications and source records attributed to C Panos.

At least 37 records · Page 2Linked to original sources
PubMed1976

Membrane studies of Streptococcus pyogenes and its L-form growing in hypertonic and physiologically isotonic media. An electron spin resonance spectroscopy approach.

Electron spin resonance spectroscopy (ESR) was used to compare the lipid organization, thermal stability and the physical state of the membrane of a human pathogen, Streptococcus pyogenes and its osmotically fragile L-form with this same L-form now adapted to grow under physiologically isotonic conditions (physiological L-form). Comparison of the hyperfine splittings of a derivative of 5-ketostearic acid spin label, I(12, 3), after incorporation into the membrane, revealed that the lipid chain rigidity of these membranes is in the order physiological L-form greater than osmotically fragile L-form greater than streptococcus. The signal intensity (of the center magnetic field line) versus temperature analysis showed two transitions for these membranes. The first with melting points of 45, 26 and 36 degrees C and second transition at 70, 63 and 60 degrees C for the physiological L-form, osmotically fragile L-form and streptococcal membranes, respectively. This same order of membrane lipid chain rigidity was seen from the cooperativities obtained for each of these systems from analysis based on the expression for an n-order reaction. The I(12, 3) and other probes with the paramagnetic group close to the methyl end of the molecule suggested that this difference in lipid chain rigidity between these organisms resides in the environment closer to the lipid head group region rather than in the hydrophobic lipid core. Another major finding was the binding of I(12, 3) at two or more different sites in each of the membranes examined. This change in lipid chain rigidity now provides an explanation to account for the survival of a previously osmotically fragile L-form in physiologically isotonic media by focusing on changes in the physical nature of its membrane. In so doing, it adds to and reinforces the speculation of the potential survival in vivo and involvement in pathogenesis of osmotically fragile aberrant forms of bacteria.

Cell Membrane↗
PubMed1976

Adaptation of an osmotically fragile L-form of Streptococcus pyogenes to physiological osmotic conditions and its ability to destroy human heart cells in tissue culture.

An osmotically fragile L-form of Streptococcus pyogenes, type 12, was quickly rendered osmotically stable by decreasing the sodium chloride content of the growth medium and with the temporary use of oleic acid. The change from osmotic fragility to stability was accompanied by changes in cell yield, generation time, saturated/unsaturated fatty acid ratio of the membrane, and cytoplasmic protein composition. Finally, this resulting osmotically stable L-form survived and was capable of rapidly destroying Girardi human heart cells in tissue culture.

Cell Survival↗
PubMed1976

Persistence, pathogenesis, and morphology of an L-form of Streptococcus pyogenes adapted to physiological isotonic conditions when in immunosuppressed mice.

Evidence obtained using nonimmunosuppressed and newborn mice suggests that the immune response of the host plays a role in the rapid removal of a physiologically isotonic L-form of Streptococcus pyogenes, since its inability to persist in vivo was not due to osmotic lysis. With mice immunosuppressed with methylprednisolone sodium succinate, viability and detection of this L-form by fluorescent antibody was prolonged for at least 2 weeks, the approximate duration of immunosuppression in these mice. However, heat-killed L-form cells only persisted for 3 days in such mice. Therefore, persistence of a viable L-form in these treated mice was not simply due to the lack of removal of L-forms by a compromised host. At no time was there any indication of illness in nonimmunosuppressed or immunosuppressed mice after L-form injection, and all internal organs, when examined macroscopically, remained normal. Thus, overt pathogenesis was not a characteristic of this L-form in a suitable host even when its immune response had been compromised. The microscopic morphology of the L-form after isolation from immunosuppressed mice changed drastically. It was typically micrococcal in appearance and exemplified the cellular variability achievable by this organism in vivo. Also, streptolysin S production was increased markedly by passage of the L-form in immunosuppressed mice. However, M protein, as a cellular component, was not detected serologically, nor was any reformation of a rigid cell wall apparent by electron microscopy after isolation of this streptococcal L-form from such mice.

Animals↗
PubMed1976

Defective synthesis of lipid intermediates for peptidoglycan formation in a stabilized L-form of Streptococcus pyogenes.

Membrane preparations obtained from a stabilized L-form of Streptococcus pyogenes are incapable of synthesizing peptidoglycan from uridine-5'-diphospho-N-acetyl-D-muramyl-L-Ala-D-iso-Glu-L-Lys-D-Ala-D-Ala and uridine-5'-diphospho-N-acetyl-D-glucosamine, in contrast with similar preparations from the parental streptococcus. Furthermore, 50-fold higher levels of lipid intermediates which serve as membrane-bound substrates for peptidoglycan synthesis are synthesized in reaction mixtures containing streptococcal membranes than with similar preparations from the L-form. These observations suggest that the inability of this stabilized L-form to form a cell wall in vivo lies, at least in part, in its failure to synthesize significant quantities of the lipid substrates for peptidoglycan synthesis.

Adenosine Triphosphate↗
PubMed1976

Membrane lipoteichoic acid of Streptococcus pyogenes and its stabilized L-form and the effect of two antibiotics upon its cellular content.

Membrane lipoteichoic acid continues to be synthesized by an osmotically fragile, stabilized L-form of Streptococcus pyogenes. Chromatographic and electrophoretic comparisons indicate that the lipid componenent of lipoteichoic acid in this L-form and its parental streptococcus is glycerophosphoryldiglucosyl diglyceride and not phosphatidylkojibiosyl diglyceride. Based upon dry weight determinations, the yield of lipoteichoic acid from the L-form is 0.19%, as compared with 0.97% from the streptococcus. When grown with bacitracin the L-form contains the same amount of teichoic acid as when grown without this antibiotic; however, its lipoteichoic acid content is reduced by 85%. Similarly, the L-form grown with novobiocin for 10 h contains only 17% of the teichoic acid found in control cells.

Bacitracin↗
PubMed1974

Incorporation of D-alanine into the membrane of Streptococcus pyogenes and its stabilized L-form.

A principal aim of this study was to explain our earlier finding of a lack of d-alanine in the glycerol teichoic acid from the membrane of a stabilized L-form of Streptococcus pyogenes (B. M. Slabyj and C. Panos, 1973. J. Bacteriol. 114:934-942). It was found that the incorporation of d-alanine into the membrane teichoic acid of S. pyogenes requires either supernatant fraction or two enzymes from supernatant fraction, stimulator (d-alanine activating enzyme) and d-alanine:membrane acceptor ligase, plus membrane fragments, ATP and Mg(2+). A similar system from the L-form is inoperative. Also, no incorporation is observed with L-form or coccal supernatant fractions when L-form membranes are used. However, d-alanine incorporation is observed when L-form enzymes are used with membrane fragments from the parental streptococcus. Thus, the L-form possesses the required soluble components for d-alanine incorporation but the L-form membrane cannot function as acceptor even though it contains d-alanine-deficient membrane teichoic acid. These results suggest that a defect has occurred in the membrane of this stabilized L-form for d-alanine incorporation into membrane teichoic acid.

Adenosine Triphosphate↗
PubMed1973

Teichoic acid of a stabilized L-form of Streptococcus pyogenes.

A stabilized L-form of Streptococcus pyogenes continues to synthesize glycerol teichoic acid. This polymer was obtained from S. pyogenes and its L-form, treated in identical fashion, and compared. Highly purified glycerol teichoic acid from only the L-form was found to be devoid of d-alanine and to have a shorter chain length. Otherwise, the glycerol teichoic acid from these two organisms was found to be a 1,3-phosphodiester-linked glycerophosphate polymer substituted with d-glucose. Evidence is presented that most, if not all, of the glycerol teichoic acid in this streptococcus lies between the wall and membrane. A possible need for the continued synthesis of a minute amount of glycerol teichoic acid by this L-form for survival is discussed in terms of the known function of teichoic acids in bacteria.

Alanine↗
PubMed1973

Protein and fatty acid composition of mesosomal vesicles and plasma membranes of Staphylococcus aureus.

Qualitatively, the protein and fatty acid composition of purified mesosomal vesicles and the plasma membrane isolated from Staphylococcus aureus ATCC 6538P are identical, the major difference between these two cellular components being only quantitative in nature. Mesosomal vesicles and plasma membranes, when subjected to acidic or neutral disk gel electrophoresis, exhibited more than 22 bands of protein. With urea-acetic acid gels, the plasma membrane had a higher concentration of "slower-migrating proteins" whereas "faster-migrating proteins" predominated in the mesosomal vesicles. With neutral disk gel electrophoresis, mesosomal vesicles exhibited one prominent protein band with an approximate molecular weight of 35,000 and which was four times greater than that found in the corresponding region on gels of the plasma membrane. Finally, fatty acid analyses by capillary column gas chromatography showed that although the fatty acid composition is the same, the fatty acid content in mesosomal vesicles is 48% greater than that of the plasma membrane. The dominant fatty acids in both of these cellular components are the iso and anteiso branched methyl C15, C17, and C19 fatty acids and comprise at least 85% of the total fatty acids extracted. These results show that distinct chemical differences exist between the mesosomal vesicles and the plasma membrane of Staphylococcus aureus.

Bacterial Proteins↗
PubMed1972

Comparative electrophoretic and amino acid analyses of isolated membranes from Streptococcus pyogenes and stabilized L-form.

Major quantitative, but not qualitative, differences in the various species of proteins in purified membranes from Streptococcus pyogenes and its stabilized L-form have been demonstrated by acidic and alkaline disc gel electrophoresis with and without urea. The fact that no significant differences in the amino acid content or composition between these two membranes could be demonstrated emphasizes that these results are probably due to changes in the relative amounts of the various species of proteins in this subcellular component. The possibility of these protein changes in the L-form membrane being related to its inability to synthesize a rigid cell wall is discussed. Finally, phage-associated lysin, routinely used for removal of the group A streptococcal cell wall, does not appear to affect the protein profile or amino acid composition of the membrane either metabolically or nonmetabolically.

Amino Acids↗
PubMed1971

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.

Amino Sugars↗
PubMed1971

Phospholipids of Clostridium butyricum. IV. Analysis of the positional isomers of monounsaturated and cyclopropane fatty acids and alk-1'-enyl ethers by capillary column chromatography.

The positional isomers of the cyclopropane fatty acids of Clostridium butyricum phospholipids have been analyzed by capillary column gas-liquid chromatography. Greater than 95% of the methylenehexadecanoic acids was the 9,10 isomer. On the other hand, 60-70% of the hexadecenoic acid precursors was the Delta(7) isomer, and the remainder was the Delta(9) isomer. Of the methyleneoctadecanoic acids 75-80% was the 11,12 isomer, with the remainder being the 9,10 isomer. There were approximately equal amounts of the Delta(9)- and Delta(11)-octadecenoic acids in the phospholipids. This study reveals a surprisingly strong specificity of the cyclopropane synthetase for the (n-7) series of monoenoic fatty acids. An analysis by capillary column chromatography of the monoenoic and cyclopropane aldehyde dimethylacetals derived from the plasmalogens (1-alk-1'-enyl-2-acyl-glycero-phosphatides) of C. butyricum revealed the presence of the same positional isomeric mixtures of the 16- and 18-carbon monoenoic residues in approximately the same ratios as were found in the fatty acids. In the formation of the cyclopropane alk-1'-enyl ethers there was also specificity for the (n-7) series, but it was not as strong as that seen in the fatty acids. The ratio of the 7,8 isomer to the 9,10 isomer was higher in the methyl-enehexadecanals than in the corresponding fatty acids. This paper extends the use of Golay capillary columns to the analysis of the positional isomers of plasmalogen aldehydes as their dimethylacetal derivatives.

Aldehydes↗