INITIAL CHARACTERIZATION OF 2 EXTRACELLULAR AUTOLYSINS FROM PSEUDOMONAS-AERUGINOSA-PAO1

Two extracellular autolysins have been detected in the spent culture s upernatants of Pseudomonas aeruginosa PAO1 by using renaturing polyacr ylamide gel electrophoresis. The two autolysins were isolated from the culture supernatant by trichloroacetic acid precipitation and were sh own to have apparent molecular masses of 26 and 29 kDa. The 26-kDa aut olysin first appears during the early exponential phase of growth and then declines sharply, while the 29-kDa autolysin first appears in the late exponential phase of growth and continues web into the stationar y phase. Fractionation of whole cells indicated that the 26-kDa enzyme was also localized within the periplasm, with a lesser amount of acti vity associated with the cytoplasmic membrane. The 29-kDa autolytic ac tivity was distributed within the cell equally between the periplasm a nd the cytoplasmic membrane. The pH optima of the isolated 26- and 29- kDa autolysins are 6.0 and 5.0, respectively. Further evidence from bo th protease susceptibility and inhibition studies confirms that these two extracellular autolysins isolated from P. aeruginosa PAO1 are sepa rate and distinct.