| dc.description.abstract | Phages are the viruses of bacteria. To complete the infection cycle, phages produce lysis proteins to overcome the bacterial cell envelope. The final barrier in Gram-negative hosts is the outer membrane (OM). We have recently identified a novel lysis protein produced by the phage PhiKT called gp28. Our previous results indicate that gp28 is produced to disrupt the outer membrane (OM). Based on similarities with cathelicidin antimicrobial peptides (CAMPs) like LL-37, such as helical content, cationic charge, membrane association, and short peptide length (<60 aa), our model is that gp28 is a phage-encoded AMP. We hypothesized that, like other CAMPs, gp28 disrupts both the IM and OM. We developed a kinetic assay using fluorescence microscopy to report membrane permeabilization. The results indicate that gp28 permeabilizes the IM before the OM. To further investigate how gp28 disrupts membranes, we conducted a mutational study of gene 28, using complementation of a spanin defect as an assay. Our results indicate that disruption of structures characteristic of CAMPs resulted in loss of function. Future work will probe subcellular localization of mutants using fluorescence microscopy to investigate determinants of membrane interaction. | |
