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INRA
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31326 Castanet Tolosan CEDEX - France

Dernière mise à jour : Mai 2018

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Internet de l'unité STLO Science et Technologie du Lait et de l'Oeuf

STLO Research Unit

How lysozyme drastically damages bacterial membranes

Lysozyme
Studies on egg white, particularly on lysozyme and ovotransferrin, all demonstrate activities against bacterial membranes from many bacteria groups. We studied how lysozyme acts on bacteria membranes.

For a long time lysozyme was only known for its antimicrobial activity against Gram-positive bacteria.

Our results on Gram-negative bacteria are:

  • Lysozyme permeabilizes both the outer and inner membranes of Escherichia coli.
  • Pore size and quantity were higher with dry-heated lysozyme compared to the native protein. 

Effect of lysozyme on Escherichia coli membranes visualised using atomic force microscopy (1 µm white bar) 

E coli K12
E. coli with native lysozyme
E coli with dry-heated lysozyme

E. coli K12    

 

E. coli with native lysozyme

E. coli with dry-heated lysozyme

 
Studies using lipopolysaccharide (LPS) and endothelial cell (CMEC) monolayer, models of the E. coli outer and inner membranes, respectively, have shown that:

  • Lysozyme has a high affinity for the LPS monolayer into which it inserts as long as polysaccharide moieties are present, causing reorganisation of the monolayer.
  • Dry-heated lysozyme has a stronger affinity for the LPS monolayer and causes more radical reorganisation than native lysozyme.
  • Lysozyme absorbs and inserts into the CMEC monolayer causing severe modifications in lipid packing.

 
Our study demonstrates the different actions of lysozyme and expands the spectrum of its activities and the environmental conditions in which this protein can act.

 

FiletGris

 

Collaborations

V. Vié • Institute of Physics – Rennes

Read more

Derde, M.; Nau, F; Lechevalier, V; Guérin-Dubiard, C; Paboeuf, G; Jan, S; Baron, F; Gautier, M; Vié, V. 2015. Native lysozyme and dry-heated lysozyme interactions with membrane lipid monolayers: Lateral reorganization of LPS monolayer, model of the Escherichia coli outer membrane. Biochimica et Biophysica Acta (BBA) - Biomembranes. 1848 (1, Part A): 174-183
http://dx.doi.org/10.1016/j.bbamem.2014.10.026

Derde, M.; Guérin-Dubiard, C; Lechevalier, V; Cochet, M F; Jan, S; Baron, F; Gautier, M; Vié, V; Nau, F. 2014. Dry-heating of lysozyme increases its activity against Escherichia coli membranes. Journal of Agricultural and Food Chemistry. 62 (7): 1692-1700.
http://dx.doi.org/10.1021/jf405155p

Derde, M.; Lechevalier, V; Guérin-Dubiard, C; Cochet, M F; Jan, S; Baron, F; Gautier, M; Vié, V; Nau, F. 2013. Hen egg white lysozyme permeabilizes Escherichia coli outer and inner membranes. Journal of Agricultural and Food Chemistry. 61 (41): 9922-9929.
http://dx.doi.org/10.1021/jf4029199

Contacts

Françoise Nau • Scientist in the Bioactivity & Nutrition team

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