The Inherent DNase of Pyocin AP41 Causes Breakdown

Pyocin AP41 degrades the chromosomal DNA in sensitive strains of Pseudomonas aeruginosa but has little effect on RNA, protein, and lipid syntheses. In vitro experiments showed that the carboxyl-terminal part of the large subunit of pyocin AP41 carries an inherent DNase that is responsible for its killing action. Pyocin AP41 is a typical S-type pyocin, proteinase-sus-ceptible bacteriocin, produced by certain strains of Pseudo-monas aeruginosa (3, 14). Biochemical studies (11) and molecular analysis of the pyocin determinant (12, 13) have shown that pyocin AP41 is a complex of two protein subunits with molecular weights of 84,000 and 10,000. The large component, as well as pyocin AP41 (LS complex), kills susceptible bacteria, such as the PAO strain. The character-istic action of pyocin AP41 is that it causes production of resident pyocins, like R2 and S2, in the PAO strain and/or bacteriophages (F116 and PS17) in their lysogenic strains in a recA-dependent way (11). In these respects, pyocin AP4