Phosphoethanolamine addition to the Heptose I of the Lipopolysaccharide modifies the inner core structure and has an impact on the binding of Polymyxin B to the Escherichia coli outer membrane.
Phosphoethanolamine (pEtN) decoration of E. coli Lipopolysaccharide (LPS) provides resistance to the antimicrobial Polymyxin B (PolB). While EptA and EptB enzymes catalyze the addition of pEtN to the Lipid A and Kdo (pEtN-Kdo-Lipid A), EptC catalyzes the pEtN addition to the Heptose I (pEtN-HeptI). In this study, we investigated the contribution of pEtN-HeptIto PolB resistance using eptA/eptB and eptC deficient E. coli K12 and its wild-type parent strains. These mutations were shown to decrease the antimicrobial activity of PolB on cells grown under pEtN-addition inducing conditions. Furthermore, the 1-N-phenylnapthylamine uptake assay revealed that in vivo PolB has a reduced OM-permeabilizing activity on the ΔeptA/eptB strain compared with the ΔeptC strain. In vitro, the changes in size and zeta potential of LPS-vesicles indicate that pEtN-HeptIreduce the PolB binding, but in a minor extent than pEtN-Kdo-Lipid A. Molecular dynamics analysis revealed the structural basis of the PolB resistance promoted by pEtN-HeptI, which generate a new hydrogen-bonding networks and a denser inner core region. Altogether, the experimental and theoretical assays shown herein indicate that pEtN-HeptIaddition promote an LPS conformational rearrangement, that could act as a shield by hindering the accession of PolB to inner LPS-targets moieties.
Universidad Andres Bello, Facultad de Ciencias Biológicas, Molecular Biophysics & Bioinformatics Group, Center for Bioinformatics and Integrative Biology (CBIB), República 239, Santiago, Chile.
Javier
J
Salazar
Universidad Andres Bello, Facultad de Ciencias Biológicas, Molecular Biophysics & Bioinformatics Group, Center for Bioinformatics and Integrative Biology (CBIB), República 239, Santiago, Chile.
Mackarenna
M
Alarcón
Universidad Andres Bello, Facultad de Ciencias Biológicas, Molecular Biophysics & Bioinformatics Group, Center for Bioinformatics and Integrative Biology (CBIB), República 239, Santiago, Chile.
Jaime
J
Huerta
Universidad Andres Bello, Facultad de Ciencias Biológicas, Molecular Biophysics & Bioinformatics Group, Center for Bioinformatics and Integrative Biology (CBIB), República 239, Santiago, Chile.
Belén
B
Navarro
Universidad Andres Bello, Facultad de Ciencias Biológicas, Molecular Biophysics & Bioinformatics Group, Center for Bioinformatics and Integrative Biology (CBIB), República 239, Santiago, Chile; Centro Interdisciplinario de Neurociencia de Valparaíso, Valparaíso, Chile. Electronic address: daniel.aguayo@unab.cl.
Daniel
D
Aguayo
D002462:Cell Membrane / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D004983:Ethanolamines / Q000737:chemistry / Q000378:metabolism*; D017353:Gene Deletion; D006539:Heptoses / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008050:Lipid A / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics / Q000378:metabolism; D011112:Polymyxin B / Q000737:chemistry*
D029968:Escherichia coli Proteins; D004983:Ethanolamines; D006539:Heptoses; D008050:Lipid A; D008565:Membrane Proteins; C121439:eptC protein, E coli; C005448:phosphorylethanolamine; C501859:EptB protein, E coli; D017853:Phosphotransferases (Alcohol Group Acceptor); D011112:Polymyxin B
Lipopolysaccharide; Phosphoethanolamine; Polymyxin