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PubMed1981

Comparative study of F-type pyocins of Pseudomonas aeruginosa.

Pseudomonas aeruginosa strain PAF41 was found to produce a new F-type pyocin, pyocin F3, the action spectrum of which was different from those of previously reported pyocins F1 and F2. These three F-type pyocins were compared with respect to their structure and biological properties. These pyocins were almost the same with regard to the structure and the dimensions, and have similar amino acid compositions and S values. The particle weights of these pyocins were also suggested to be similar. Analyses of subunit proteins by SDS-polyacrylamide slab gel electrophoresis showed that these pyocins were composed of 5 major (bands 1, 2, 3, 4, and 6) and 2 minor (bands 5 and 7) subunit proteins and that no difference in the mobilities of these subunit proteins could be detected among the pyocins except that of the second major subunit protein (band 4), which did differ. Pyocins F1, F2, and F3 were immunologically cross-reactive, and carried common antigens as well as specific ones. It was shown that band 6 was a common antigen among the three pyocins and that band 4 was antigenically different in pyocins F1 and F3 by immunological reaction after protein blotting. Electron microscopic observation of pyocin particles treated with anti-sera revealed that the common antigens were located on the rod part and the specific ones were on the fiber part. Pyocin F3 was neutralized by both anti-F3 and anti-F1 sera showing apparent first order rate kinetics, whereas the neutralization for pyocin F1 by these sera did not show such kinetics, but a considerable increment of pyocin F1 activity was observed when small amounts of the sera were added. The increment seemed to be due to the antibodies common to pyocins F1, F2, and F3. A phage, which had a flexuous rod-like tail, was found to be immunologically cross-reactive with the three pyocins and was named KF1.

Amino Acids↗
PubMed1980

Comparative study on R-type pyocins of Pseudomonas aeruginosa.

Four R-type pyocins (R1, R2, R3, and R4) produced by different Pseudomonas aeruginosa strains were compared with respect to their structure and action methanism. It is known that these bacteriocins have structures similar to contractile bacteriophage tails and serologically cross-react with each other, but they are distinguished according to difference in range of sensitive strains. All these pyocins were shown to arrest the synthesis of protein and nucleic acid in sensitive cells, as previously reported for pyocin R1. Action of pyocin R3 was shown to require calcium ion. Although antiserum prepared against one pyocin neutralized other R-type pyocins as well as the homologous pyocin, some differences in antigen specificity were found between pyocin R1 and pyocin R2 and R3 antibody blocking assays. Electron microscopic observation of pyocin particles treated with the antiserum pre-absorbed with heterologous pyocin revealed that specific antigens were located on the distal portion of the fibers. Comparison of protein composition showed these pyocins to be composed of essentially similar subunit proteins but a subunit protein supposed to be a main constituent of the fiber was different in its molecular weight among these pyocins. These results suggest that the main structural difference of these pyocins is to be found in the fiber.

Bacteriocins↗
PubMed1993

Molecular structures and functions of pyocins S1 and S2 in Pseudomonas aeruginosa.

Pyocins S1 and S2 are S-type bacteriocins of Pseudomonas aeruginosa with different receptor recognition specificities. The genetic determinants of these pyocins have been cloned from the chromosomes of P. aeruginosa NIH-H and PAO, respectively. Each determinant constitutes an operon encoding two proteins of molecular weights 65,600 and 10,000 (pyocin S1) or 74,000 and 10,000 (pyocin S2) with a characteristic sequence (P box), a possible regulatory element involved in the induction of pyocin production, in the 5' upstream region. These pyocins have almost identical primary sequences; only the amino-terminal portions of the large proteins are substantially different. The sequence homology suggests that pyocins S1 and S2, like pyocin AP41, originated from a common ancestor of the E2 group colicins. Purified pyocins S1 and S2 make up a complex of the two proteins. Both pyocins cause breakdown of chromosomal DNA as well as complete inhibition of lipid synthesis in sensitive cells. The large protein, but not the pyocin complex, shows in vitro DNase activity. This activity is inhibited by the small protein of either pyocin. Putative domain structures of these pyocins and their killing mechanism are discussed.

Amino Acid Sequence↗
PubMed1991

Pyocin typing of Pseudomonas aeruginosa isolates from children with cystic fibrosis.

Pyocin typing and serotyping of 433 strains of Pseudomonas aeruginosa from children with cystic fibrosis (CF) showed that pyocin type 9 was predominant, particularly in association with polyagglutinating serotype. The common pyocin groups, 1, 5 and 10, made up only 20% of these isolates in contrast to reported rates of up to 89% in other studies using non-CF strains. No strains of pyocin type 3 were found. Polyagglutinating strains made up 72% of strains from patients colonized with P. aeruginosa for more than 12 mths. Pyocin type 9 was associated with 93% of polyagglutinating strains. The parallel between pyocin type 9 and polyagglutinating serotype suggests that these may both be characteristics acquired by P. aeruginosa colonizing patients with CF. Because of confounding between duration of colonization and exposure to cross-infection, this study does not allow definition of the role of cross-infection in determining the characteristics of these strains in most patients. In siblings, however, evidence supports a role for cross-infection either between siblings or from a common source. In 6 pairs of siblings studied, each pair had at least 1 pyocin group in common concurrently, either at entry to the study or after an interval of several months. Identical and unusual pyocin groups were recognized in samples obtained on the same day from pairs of siblings. More studies are needed to compare results of pyocin typing with methods such as genome fingerprinting to characterize these strains and determine whether the observed distribution of pyocin groups in CF isolates is related to cross-infection or whether the combination of pyocin type 9 with polyagglutinating serotype is a characteristic of CF strains.

Adolescent↗
PubMed1975

Preferential inhibition of lipid synthesis by the bacteriocin pyocin S2.

The effects of pyocin S2, a bacteriocin produced by Pseudomonas aeruginosa strain M47, on several processes in susceptible bacterium have been examined. Lipid synthesis, measured in terms of [32P]phosphate, [14C]acetate or [2-3H]glycerol incorporation into lipid fractions, was halted almost completely soon after pyocin S2 addition. When cell suspensions were treated with various amounts of pyocin S2, the extent of inhibition of lipid synthesis was proportional to the ratio of killed bacteria. Protein synthesis was not essential for the inhibition. Degradation of lipid due to pyocin S2 was not detected. Pyocin S2 also affected protein and nucleic acid syntheses, but these inhibitions appeared with a delay of about 10 min after the cessation of lipid synthesis. The effect of trypsin [EC 3.4.21.4] on the viability of cells which had adsorbed pyocin S2 was also investigated: the cells went through a period when the destruction of pyocin S2 by trypsin restored the colony-forming ability of the cells (stage I). Then transition to a second state in which the cells lost viability irrespective of trypsin treatment (stage II) took place. The transition from stage I to stage II depended on the energy metabolism of the cells and followed first-order kinetics with a rate proportional to the number of killing units of adsorbed pyocin S2. The residual capacity for lipid synthesis in cells which had adsorbed pyocin S2 after trypsin treatment at various times indicated that lipid synthesis was inhibited only in the cells at stage II of pyocin S2 action.

Acetates↗
PubMed1980

Cytotoxicity of pyocin S2 to tumor and normal cells and its interaction with cell surfaces.

Cytotoxicity and adsorption of pyocin S2 produced by Pseudomonas aeruginosa M47 (PAO 3047) to virally transformed mammalian cells, human malignant cells and normal cells in the same species were studied. Pyocin S2 inhibited the growth of not only tumor cells (XC, TSV-5, mKS-A TU-7, HeLa-S3 and AS-II cells) but also normal cells (BALB/3T3 and BHK 21 cells). The inhibitory effects on the cells increased with an increase of pyocin S2 activity. On the other hand, there were some tumor cells (155-4 T2 and HCG-27 cells) and normal cells (normal rat kidney and human embryo lung cells) which were resistant to pyocin S2. The pyocin S2 activity was neutralized by the cell membrane preparations from pyocin S2-sensitive cells, but not by those from pyocin-resistant cells. This neutralization ability was inhibited by high concentrations of D-galactose, N-acetyl-D-galactosamine and N-acetyl neuraminic acid and completely destroyed by periodate and neuraminidase. The inhibition by the saccharides was concentration dependent. These results suggest that the toxicity of pyocin S2 in the cell membrane and further, that the carbohydrate moiety, especially of D-galactose, N-acetyl-D-galactosamine and sialic acid, may play an important role as an initial binding site for pyocin S2.

Acetylgalactosamine↗
PubMed1979

Biochemical properties of a new flexuous bacteriocin, pyocin F1, produced by Pseudomonas aeruginosa.

Pseudomonas aeruginosa strain P15 produces not only pyocin R1 and phage PS10, but also a substance having a flexuous rod structure, the nature of which is so far unknown. A variant strain (P15--40) was obtained which produced these flexuous particles more effectively than the original strain, and the particles were purified to homogeneity and investigated. Several strains of P. aeruginosa were found to be killed by the particles. It was concluded that the flexuous rod-like particles are not related to pyocin R1 or phage PS10, but represent a new pyocin, which we have designated as pyocin F1. Pyocin F1 showed a different action spectrum and a different pattern on SDS-polyacrylamide gel electrophoresis from either pyocin R1 or phage PS10. The killing activity of pyocin F1 was of single-hit type. The activity was not affected by anti-R1, anti-R1-core or anti-PS10, or by DNase, RNase, pronase or trypsin, but was completely destroyed by treatment at 70 degrees C for 10 min. Some cofactor was required for the adsorption of this pyocin on sensitive bacteria. Another flexuous bacteriocin was also found and named pyocin F2.

Bacteriocins↗
PubMed1989

Relationship of antibiotic resistance phenotype to the R-pyocin susceptibility pattern in clinical isolates of Pseudomonas aeruginosa.

One hundred sixteen clinical isolates of Pseudomonas aeruginosa were collected from 7 hospitals in Athens. All strains were studied for their susceptibility to cefotaxime, ceftazidime, carbenicillin, aztreonam, imipenem, nalidixic acid, ciprofloxacin, gentamicin, and chloramphenicol. In addition, the R-pyocin susceptibility pattern was determined and the strains were O-serotyped and tested for their agglutination in acriflavine. The isolates included 53 strains resistant to both gentamicin and carbenicillin, 13 to carbenicillin only, 20 to gentamicin only, and 30 sensitive to gentamicin and carbenicillin. The multiresistant isolates displayed relatively higher resistance to all other antibiotics except aztreonam and cefotaxime. Remarkably 30 out of 53 multiresistant isolates reacted with one pyocin only, namely pyocin R2. This R-pyocin response was not encountered in any other strains of the other antibiotic resistance phenotypes. These isolates belonged to the 0-12 serogroup. The 0-12 serogroup was represented only in a minority of strains giving other R-pyocin reactions. It is interesting that strains reacting with pyocin R5 only were mostly susceptible to antibiotics. The results clearly indicate lipopolysaccharide-core mutations in multiresistant clinical isolates of P. aeruginosa. Despite the fact that the R-pyocin resistance pattern can not define the precise possible defect, the multiple and high level resistance associated with R2-pyocin reaction seems to be an interesting trait.

Bacteriocins↗
PubMed1984

Phenotypic mixing of pyocin R2 and bacteriophage PS17 in Pseudomonas aeruginosa PAO.

Previous results indicate that a group of bacteriocins in Pseudomonas aeruginosa, named R-type pyocins, have a structure resembling bacteriophage tails and share some serological homology with certain bacteriophages. This paper presents genetic evidence which strongly suggests that components of pyocin R2, an R-type pyocin of P. aeruginosa PAO, and tail components of bacteriophage PS17 are interchangeable. Complementation tests with pyocin R2-deficient mutants of PAO and ts mutants of PS17 revealed that various phenotypic interactions occur between the pyocin and bacteriophage in PAO cells lysogenized or infected with PS17. (i) Certain pyocin R2-deficient mutations were phenotypically suppressed in cells carrying PS17 prophage. (ii) A temperature-sensitive mutant of PS17, tsQ31, was phenotypically suppressed in PAO cells treated with mitomycin C. (iii) Phenotypically mixed phages with receptor and serological specificities of pyocin R2 were formed in PS17 lysogens of certain pyocin R2-deficient mutants.

Bacteriocins↗
PubMed1978

Mode of action of pyocin R1.

The effects of pyocin Rl on transport systems and syntheses of macromolecules in Pseudomonas aeruginosa strain P14 were studied under two conditions, 0.4 mM and 40 mM Magnesium ions. In the presence of 0.4 mM magnesium ions, the incorporation of [14C]leucine into protein and the uptake of [14C]leucine into the leucine pool were completely inhibited by pyocin. Furthermore, [14C]leucine which had been taken up into the leucine pool was depleted by pyocin. Comparing the concentration of amino acid within cells with that in the medium, it was concluded that the active transport in P14 cells was inhibited completely by pyocin. Such an effect of pyocin Rl on transport systems was not specific to leucine but common to many amino acids and uridine. On the other hand, under the condition of 40 mM magnesium ions, [14C]-leucine once accumulated was not depleted by pyocin, but uptake of [14C]leucine into the leucine pool stopped immediately while incorporation of [14C]leucine into protein continued at a considerably reduced rate; therefore the machinery for protein synthesis was not directly inhibited by pyocin. It is suggested that the loss from the amino acid pool in cells brings about the rapid cessation of protein synthesis under the condition of 0.4 mM magnesium.

Bacterial Proteins↗
PubMed1994

Cytotoxin-converting phages, phi CTX and PS21, are R pyocin-related phages.

phi CTX is a temperate phage of Pseudomonas aeruginosa harbouring the ctx gene that encodes cytotoxin (CTX). We identified phi CTX as an R pyocin-related phage, by serological and molecular analysis, based on the findings that the infectivity of the phage was inhibited with the antisera directed R pyocins and R pyocin-related phages and that the phi CTX genome showed DNA homology to the genome of PS17 (a representative of the R pyocin-related phages) as well as to the pyocin R2 genes. Another new CTX-converting, R pyocin-related phage named PS21 was isolated from a CTX-producing strain of P. aeruginosa, suggesting the distribution of the ctx gene by certain members of R pyocin-related phage family.

ADP Ribose Transferases↗
PubMed1977

Pyocin sensitivity of Neisseria gonorrhoeae and its feasibility as an epidemiological tool.

Pyocin inhibition of Neisseria gonorrhoeae and its feasibility as a gonococcal typing scheme were examined. Mitomycin C-induced pyocin lysates of Pseudomonas aeruginosa were able to selectively inhibit the growth of gonococcal strains. The particles associated with the inhibitory activity were non-dialyzable, heat labile, Pronase sensitive, trypsin resistant, and of large molecular weight by membrane and gel filtration techniques. The inhibitory activity was shown to be specific by absorption with sensitive and insensitive strains of N. gonorrhoeae and P. aeruginosa. Partial purification of pyocin lysates by ammonium sulfate precipitation followed by ultracentrifugation revealed phagelike particles consistent with high-molecular-weight R-type pyocines. These particles were associated with increased inhibitory activity and could be seen associated with the gonococcal cell surface. One hundred and six gonococcal strains could be differentiated on the basis of their sensitivity of 23 pyocin extracts. Thirty different patterns of pyocin inhibition were seen. Isolates from different body sites from the same patient could generally be identified as being similar strains. Strains isolated from known consorts had the same patterns. In general, agreement between pyocin typing and available epidemiological information was good.

Bacteriocins↗
PubMed1983

Antigenic specificity and heterogeneity of lipopolysaccharides from pyocin-sensitive and -resistant strains of Neisseria gonorrhoeae.

Homologous antisera were raised against lipopolysaccharides (LPSs) isolated from pyocin 103-sensitive JW31 strain Neisseria gonorrhoeae and its isogenic, pyocin-resistant variant, JW31R. Changes in immunochemical reactivity of LPS antigen associated with pyocin-resistance were examined by enzyme-linked immunosorbent assay, employing homologous and heterologous anti-LPS immune sera. The acquisition of pyocin 103 resistance is accompanied by a loss in LPS antigen reactivity with homologous anti-LPS. The variant LPS of pyocin 103-resistant mutants is immunogenic and displays a new, distinct antigenic specificity shared with other pyocin 103-resistant variant gonococcal strains. The acquisition of pyocin 103 resistance by JW31 strain gonococci is also accompanied by a striking loss of LPS cross-reactivity with antistreptococcal polysaccharide reagents having an antibody combining site specificity directed against the chemically defined lactose polymer from Streptococcus faecalis cell wall and pneumococcal type 14 capsular polysaccharide. When examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and sodium dodecyl sulfate-urea-polyacrylamide gel electrophoresis, JW31 and JW31R LPSs show banding patterns characteristic of microheterogeneous, rough-type LPS devoid of O-side chains. Immunoblot transfer analysis of gel-separated gonococcal LPS antigens shows a difference in the pattern of antibody binding by homologous versus cross-reactive anti-LPS, which suggests a heterogeneity in the distribution of cross-reactive determinants among LPS molecules.

Antigens, Bacterial↗
PubMed1989

Genetic comparison of bacteriophage PS17 and Pseudomonas aeruginosa R-type pyocin.

PS17 is a bacteriophage of Pseudomonas aeruginosa that is serologically cross-reactive with phage tail-like bacteriocins called R-type pyocins. In addition to having immunological cross-reactivity, certain genes are functionally complementable between PS17 and R-type pyocins. To compare the genetic structures of PS17 and R-type pyocins, a physical map of PS17 genes was constructed by cloning phage DNA fragments on RSF1010-derived vector plasmids. The head and tail gene clusters were tandemly arrayed and together occupied about half of the 41-kilobase-pair PS17 chromosome. With use of these phage clones, the following results were obtained with respect to the genetic relationship between PS17 and R-type pyocins: (i) serological cross-reaction between PS17 and pyocin occurred for the major sheath protein and two components of the fiber, (ii) a certain pyocin mutation was complemented by cloned phage fragments, and (iii) the phage DNA fragment carrying sheath and core tube genes was shown to hybridize to the DNA fragment carrying the pyocin R2 genes.

Bacteriocins↗
PubMed1980

[Pyocin production by bacillus pyocyaneus and sensitivity of strains of different origin to them].

Using the method proposed by Gillies and Govan and their indicator strains, 342 P. aeruginosa strains isolated from the patients were studied in respect to their pyocinogenicity and typed according to the production of different types of pyocins. Besides, in 206 cultures the pyocin sensitivity of 16 standard P. aeruginosa strains (5 strains obtained from Govan and 11 strains provided by the authors) was determined. All the tested cultures fell into 23 pyocin types; of these, types I and X occured most frequently, 56 strains identified by means of indicators could not be typed due to the fact that the corresponding pyocin types were absent in Govan's scheme. The cultures isolated from the patients and the environmental objects during the outbreak of P. aeruginosa in a hospital were proved to belong to the same pyocin type (III). The double typing of the cultures, according to pyocin production and pyocin sensitivity, allowed to determine individual characteristics of 75% of the tested cultures.

Bacteriocins↗
PubMed1980

Effect of iron concentration in the growth medium on the sensitivity of Pseudomonas aeruginosa to pyocin S2.

The iron concentration in the growth medium was found to affect the susceptibility of Pseudomonas aeruginosa PML1550 to pyocin S2, a bacteriocin. The efficiency of killing by pyocin S2 was very low when the indicator cells were grown in an iron-rich medium. The capacity of these cells to adsorb pyocin S2 was reduced. Cultivation under limitation of iron (1 microM or less) was necessary to produce a fully sensitive cell population. The growth under iron limitation was accompanied by the appearance of four protein components in the outer membrane of the cells. Nine mutants resistant to pyocin S2 were isolated and their outer membranes were analyzed. They all lacked one component (Fe-b protein) as well as the adsorption capacity for pyocin S2. These findings suggest a possible role of this protein as the receptor for pyocin S2.

Bacteriocins↗
PubMed1976

Treatment of Pseudomonas aeruginosa infections with pyocines.

The interactions of a contractile, a filamentous and a small pyocine with a sensitive strain of Pseudomonas aeruginosa (no. P14) were examined in vivo. The purification procedure used yielded high-activity pyocine preparations that were not toxic to mice. The inhibitory activity of such preparations, when injected into mice by various routes, was retained for up to 24 h. However, high molecular-weight pyocines given intraperitoneally in the presence of a lethal dose of strain P14 administered by the same route did not prevent the fatal outcome of infection unless they are given before or together with the bacteria. The small pyocine had no protective effect. In burned mice infected with strain P14, topical application of a filamentous pyocine failed to improve the chances of survival. The results suggest that there is little future for pyocine therapy.

Administration, Topical↗
PubMed1975

Defective pyocin particles produced by some mutant strains of Pseudomonas aeruginosa.

Mutants of Pseudomonas aeruginosa, defective in the production of active R-type pyocins, were isolated from pyocinogenic strains and their products were characterized. Polysheath-like structures were found in induced lysates of 29 out of 42 mutants. Two mutants (strain P15-16 and M189) were found to produce special defective particles, which were characterized in detail. The other 11 mutants did not produce significant amounts of any structure visible under an electron microscope. Serum blocking powers were found in lysates from P15-16 and M189 to significant amounts. Defective particle produced by strain P15-16 lacked the sheath component, whereas M189 had morphological defects at the junction between sheath and baseplate, and also in the architecture of baseplate. Both defective particles could adsorb to the surface of bacteria, that were sensitive to pyocin, at the tip of their fibers without killing cells. All M189 particles attached to the bacteria had the extended sheaths. Therefore, attachment to the bacteria by fibers is not sufficient to kill cells, and contraction of sheath must occur after the initial adsorption by fibers for pyocin to express its biological activity. Defective particles of strain P15-16, which was derived from strain P15 (a pyocin R1 producer), could be converted to active forms by an in vitro complementation reaction with extracts from certain mutants originated from strain PAO (a pyocin R2 producer). This result indicated the exchangeability of components between R-type pyocins belonging to the different groups.

Adsorption↗