| dc.description.abstract | Spanins are required for the last step in bacteriophage lysis: the disruption of the outer membrane. However, bioinformatic analysis has shown 15 percent of phages lack a spanin gene, which suggests an alternate mechanism of outer membrane disruption. To address this, we selected virulent podophage PhiKT as a spanin-less exemplar and tested PhiKT genes for outer membrane disruption during lysis. Hypothetical novel gene 28 causes outer membrane disruption when co-expressed with PhiKT lysis genes and complements the lysis defect of a λ spanin mutant. Gp28 is a 56 aa cationic peptide with predicted amphipathic helical structure and is associated with the particulate fraction after lysis. Urea and KCl washes did not release gp28 from the particulate, suggesting a strong hydrophobic interaction with the membrane. Furthermore, membrane interaction was demonstrated using functional gp28-sfGFP, which localized to the periphery of the cell. Based on this data, gp28 represents a new class of lysis proteins, a disruptin – an antimicrobial peptide produced to destroy the outer membrane during lysis. This is the first reported phage-encoded antimicrobial peptide. | |
