1.E.21 The Listeria Phage A118 Holin (Hol118) Family
Listeria monocytogenes bacteriophage A118 encodes a native holin, hol118, of 93 aas exhibiting 3 putative TMS. When cloned into lambda (λΔSthf) devoid of the S holin, it caused very late cell lysis, beginning 80 min. after induction (Vukov et al., 2003). Hol118 appeared in the cytoplasmic membrane shortly after infection. A second translational start codon (AUG-3) at nucleotide position 40 in the gene gives rise to a second gene product of 83 aas lacking TMS1 (Hol118(83)). It is produced with the full length protein, appears in the membrane, cannot support lambda lysis, and inhibits lysis by Hol118. This dominant inhibitor presumably determines the time of lysis (Vukov et al., 2003). A homologue is found in L. innocua.
The reaction probably catalyzed is:
small molecules + autolysin (in) → small molecules + autolysin (out)
Putative holin of Dehalococcoides sp GT
Uncharacterized protein of Facklamia hominis
Holin of Entereococcal phage BC-611
Putative holin of 88 aas and 3 TMSs
Putative holin of Lysinibacillus fusiformi
Holin, hol118 of 96 aas and 3 TMSs (Kuo et al. 2009). A stably engineered holin-expressing suicidal attenuated strain of Listeria monocytogenes has been used to deliver proteins and DNA to mammalian intestinal epithelial cells (Kuo et al. 2009).
hol118 of Listeria monocytogenes phage A118
Putative holin of Bifidobacterium dentium