Studies on the Pyocins of Pseudomonas aeruginosa: Morphology and Mode of Action of Contractile Pyocins

Abstract

S U M M A R YThe adsorption and inhibitory action of pyocin 21 on sensitive cells of Pseudonzonas aeruginosa (P. pyocyanea) were observed by fluorescence microscopy and by using agar cultures. By electron microscopy, preparations from four pyocinogenic strains of P. aeruginosa were seen to include contracted and uncontracted particles, isolated tail cores and sheaths, The importance of adsorption and contraction of the particles on the surface of sensitive bacteria for the inhibitory action of these pyocins is suggested by the following evidence : ( I ) Particles adsorbed to sensitive bacteria at o "C, but contraction of particles was not then observed and the bacteria were not disrupted. ( 2 ) Pyocin particles did not adsorb to pyocin-resistant bacteria. (3) The ability to adsorb to sensitive bacteria and to kill them was absent after removal of the contractile sheath with sodium dodecyl sulphate. (4) When treated with homologous antiserum, pyocin activity was neutralized and the agglutinated particles remained unadsorbed and uncontracted. (5) Bacterial receptors for contractile pyocins contain lipopolysaccharide ; such extracts from sensitive, but not from resistant, cells of P. aeruginosa inactivated pyocins, and contracted particles were seen adsorbed to lipopolysaccharide fragments.

Pore-forming pyocin S5 utilizes the FptA ferripyochelin receptor to kill Pseudomonas aeruginosa

“…Furthermore, strains are not limited in the number of pyocins they can produce (e.g. the PAO1 strain can produce three S-type pyocins: S2, S4 and S5) (Govan, 1974;Ling et al, 2010;Michel-Briand & Baysse, 2002;Parret & De Mot, 2002).…”

“…The bacteriocins produced by Pseudomonas species are called pyocins, and, in contrast to colicins whose genes are plasmid-borne, the pyocin genes are found in the chromosome (Sano & Kageyama, 1984;Shinomiya et al, 1983). Expression of the pyocin genes is induced by stress or mutagenic agents, such as UV radiation, mitomycin C treatment and treatments that cause DNA damage (Govan, 1974;Jacob, 1954;Kageyama, 1964). There are three types of pyocins, based on their structure: R-type, F-type and S-type.…”

Sensitivity of Neisseria Gonorrhoeae to Partially Purified R-Type Pyocines and a Possible Approach to Epidemiological Typing

“…Because the preparations used in Sidberry and Sadoffs studies were equivalent to our crude lysates, some of the inhibition by R2 and R3 pyocines that they observed with a few gonococcal strains may have been due to the presence of material other than the R-type pyocines. The receptor site for the R-type pyocines is in the lipopolysaccharide (LPS) (LPS) of Pseudomonas (Ikeda and Egami, 1973;Govan, 1974a;Koval and Meadow, 1977) and a similar location has been suggested for Neisseria (Sidberry and Sadoff, 1977). Table VIII is based on Kageyama's (1975) proposed pyocine receptor sites for his groups R1-R5 in the LPS of Pseudomonas.…”

“…Pyocine preparations were obtained by a modification of the method of Govan (1974a). From an overnight nutrient-broth culture, 2 ml was added to 25 ml of sodium glutamate broth(SGB) whichcontained sodiumglutamate 20g, glucose(20% w/v solution) 20 ml, magnesium sulphate (MgS04 7H20) 0.1 g, disodium hydrogen phosphate (Na2HP04.12H20) 5-63 g, potassium dihydrogen phosphate (KH2P04) 0.25 g, calcium nitrate 10 mg, yeast extract 1 g, and distilled water to 1 litre.…”

Sensitivity of Thermophilic Campylobacters to R-type Pyocines of Pseudomonas Aeruginosa

“…The R-type pyocines were induced and partially purified as described previously (Blackwell et al, 1979), after the method of Govan (1974). Sensitivity to R-type pyocines was determined by placing drops (15 pl) of a 1 in 2 dilution of each pyocine preparations on to plates of (1) tryptone soya agar supplemented with 5% (v/v) of defibrinated horse-blood, (2) nutrient agar (Columbia Agar Base, Oxoid) containing agar 1% (w/v), and (3) similar nutrient agar containing agar 2% (w/v).…”