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1.E.20 The Pseudomonas aeruginosa Hol Holin (Hol Holin) Family

The hol gene (PRF9) product (117 aas) of Pseudomonas aeruginosa PAO1 exhibits a hydrophobicity profile similar to holins of P2 and φCTX phages with two peaks of hydrophobicity that might correspond to either one or two TMSs. Hol functions in conjunction with the lytic enzyme, Lys (PRF24; BAA83168, 209 aas). Hol by itself, when expressed in a broad host-range expression vector under IPTG control exhibited strong lytic activity in both P. aeruginosa and E. coli. Expression of the lys gene plus chloroform (but not minus chloramphenicol) yielded cell lysis. In another expression vector, coexpression of hol and lys induced lysis under conditions where neither gene alone induced lysis (Nakayama et al., 2000). The hol-lys gene system therefore is believed to constitute a chromosomally-encoded autolysis system.

The reaction probably catalyzed by Hol is:

Autolysin (Lys)in → Autolysin (Lys)out

This family belongs to the: Holin Superfamily III.

References associated with 1.E.20 family:

Nakayama, K., K. Takashima, H. Ishihara, T. Shinomiya, M. Kageyama, S. Kanaya, M. Ohnishi, T. Murata, H. Mori, and T. Hayashi. (2000). The R-type pyocin of Pseudomonas aeruginosa is related to P2 phage, and the F-type is related to lambda phage. Mol. Microbiol. 38: 213-231. 11069649
Wang, D., J.M. Yu, R.J. Dorosky, L.S. Pierson, 3rd, and E.A. Pierson. (2016). The Phenazine 2-Hydroxy-Phenazine-1-Carboxylic Acid Promotes Extracellular DNA Release and Has Broad Transcriptomic Consequences in Pseudomonas chlororaphis 30-84. PLoS One 11: e0148003. 26812402