title: Role of the cell envelope in the antibacterial activities of polymyxin B and polymyxin B nonapeptide against Escherichia coli.
abstract: The role of membrane permeabilisation and disruption in the mechanism of action of some polymyxin analogues against Gram-negative organisms is contentious. The effects of polymyxin B (PMB) and its analogue polymyxin B nonapeptide (PMBN) on Escherichia coli envelopes should correlate, but previous work by other workers suggests that PMBN has a different mode of action. This study has reassessed the biochemical techniques used previously and has shown that, in contrast to previous studies, PMBN (a well-characterised antibacterial synergist) readily releases periplasmic proteins and lipopolysaccharide from treated E. coli at subinhibitory concentrations in normal physiological buffer conditions. We conclude that, when tested with appropriate methodology, PMBN closely correlates with the early effects of PMB on the cell envelope of E. coli and this study shows that it is now consistent with the accepted interactions of membrane-active agents against Gram-negative cells.
authors: Department of Biomedical Sciences, Faculty of Health and Allied Sciences, National University of Malaysia (UKM), 53100 Kuala Lumpur, Malaysia.
authors: Ahmad Z
authors: AZ
authors: Sahalan
authors: Ronald A
authors: RA
authors: Dixon
mesh_terms: D002462:Cell Membrane / Q000187:drug effects*; D002463:Cell Membrane Permeability / Q000187:drug effects*; D002511:Cephalosporins / Q000378:metabolism; D004926:Escherichia coli / Q000187:drug effects*; D029968:Escherichia coli Proteins / Q000378:metabolism; D008070:Lipopolysaccharides / Q000378:metabolism; D009596:Nitrophenols / Q000378:metabolism; D033903:Periplasmic Proteins / Q000378:metabolism; D011112:Polymyxin B / Q000031:analogs & derivatives* / Q000494:pharmacology*; D011135:Polysaccharides, Bacterial / Q000378:metabolism; D013997:Time Factors
chemical_list: D002511:Cephalosporins; D029968:Escherichia coli Proteins; D008070:Lipopolysaccharides; D009596:Nitrophenols; D033903:Periplasmic Proteins; D011135:Polysaccharides, Bacterial; C038934:polymyxin B nonapeptide; C021720:nitrocefin; D011112:Polymyxin B