Factors Influencing the Adsorption of Bacteriophage 2 to Cells of Pseudomonas aeruginosa

Abstract

Phage 2 adsorbed to Pseudomonas aeruginosa strain BI in 5 mM Tris buffer, providing that cations like Na+, Mg2+, or Ca2+ were present. Adsorption was observed over a broad pH range, reaching a maximum level around pH 7.5, which coincided with the pH required for maximal activity of the phage 2-associated slime polysaccharide depolymerase. Mutants of strain BI and other strains of P. aeruginosa possessing slime layers that were devoid of phage 2 depolymerase substrate were incapable of adsorbing phage 2. On the other hand, those strains containing substrate for the phage 2 depolymerase in the slime layer were capable of adsorbing phage 2. The same relationship of phage depolymerase-substrate interaction to phage adsorption was observed with Pseudomonas phage 8, which possesses a depolymerase that differs in its specificity from the phage 2 depolymerase. The receptor-like activity of purified slime containing the specific substrate for the phage-associated depolymerase was demonstrable by its ability to inactivate phage. However, receptor-like activity or phage inactivation was not observed with those slimes that were devoid of the depolymerase substrate.

Studies on the Bacteriophage 2 Receptors of Pseudomonas aeruginosa

“…The chemical moieties responsible for the inactivation of phage 2 have not been identified. It has also been suggested that interaction between the phage 2-associated SPB depolymerase and its specific substrate in the slime layer may play a role in the adsorptive process (22).…”

“…Resistant colonies did not release phage 2 when exposed to the same dose of UV irradiation. Resistant colonies were labeled as previously described (22) and lysogenic colonies were numbered according to their order of isolation. Indistinguishable by colonial morphology, the relationship between wild-type strain BI, phage 2-resistant mutants of strain BI, and phage 2-lysogenized BI was demonstrated by the induction of prophage 29 present in all three strains.…”

Localization and functional role of the pseudomonas bacteriophage 2 depolymerase

“…'703 Localization of the phage-associated depolymerase. Evidence has been presented indicating a close structural association of the depolymerase with the phage 2 particle (6), and the likelihood that the depolymerase functions in the initial attachment of phage (27). It therefore became of great importance to determine a more precise location of the enzyme on the phage particle.…”

“…The possible functional role of the phage 2 depolymerase in the initial attachment of the phage to host cell is supported by experimental data (27). Analysis of several strains of P. aeruginosa indicated that only those strains containing substrate for the specific depolymerase carried by phage were capable of adsorbing phage.…”

“…The supernatant fluids were diluted and plated on wild-type strain BI to determine the number of unadsorbed or free phage particles. An adsorption medium composed of 5 mM Tris buffer (pH 7.4), supplemented with 0.1 M sodium chloride and 0.01 M magnesium sulfate, was also used in place of TSB (27).…”