The role of protein hydrophobicity in thionin–phospholipid interactions: a comparison of α1 and α2-purothionin adsorbed anionic phospholipid monolayers

Luke A. Clifton, Michael Sanders, Christian Kinane, Tom Arnold, Karen J. Edler, Cameron Neylon, Rebecca J. Green, Richard A. Frazier

Research output: Contribution to journalArticle

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Abstract

The plant defence proteins α1- and α2-purothionin (Pth) are type 1 thionins from common wheat (Triticum aestivum). These highly homologous proteins possess characteristics common amongst antimicrobial peptides and proteins, that is, cationic charge, amphiphilicity and hydrophobicity. Both α1- and α2-Pth possess the same net charge, but differ in relative hydrophobicity as determined by C18 reversed phase HPLC. Brewster angle microscopy, X-ray and neutron reflectometry, external reflection FTIR and associated surface pressure measurements demonstrated that α1 and α2-Pth interact strongly with condensed phase 1,2-dipalmitoyl-sn-glycero- 3-phospho-(1′-rac-glycerol) (DPPG) monolayers at the air/liquid interface. Both thionins disrupted the in-plane structure of the anionic phospholipid monolayers, removing lipid during this process and both penetrated the lipid monolayer in addition to adsorbing as a single protein layer to the lipid head-group. However, analysis of the interfacial structures revealed that the α2-Pth showed faster disruption of the lipid film and removed more phospholipid (12%) from the interface than α1-Pth. Correlating the protein properties and lipid binding activity suggests that hydrophobicity plays a key role in the membrane lipid removal activity of thionins.
Original languageEnglish
Pages (from-to)13569-13579
JournalPhysical Chemistry Chemical Physics
Volume14
Issue number39
DOIs
Publication statusPublished - 21 Oct 2012

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Thionins
Hydrophobicity
hydrophobicity
lipids
Monolayers
Phospholipids
proteins
Lipids
Proteins
interactions
Surface measurement
Membrane Lipids
Pressure measurement
liquid air
wheat
Brewster angle
Glycerol
pressure measurement
glycerols
Microscopic examination

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The role of protein hydrophobicity in thionin–phospholipid interactions: a comparison of α1 and α2-purothionin adsorbed anionic phospholipid monolayers. / Clifton, Luke A.; Sanders, Michael; Kinane, Christian; Arnold, Tom; Edler, Karen J.; Neylon, Cameron; Green, Rebecca J.; Frazier, Richard A.

In: Physical Chemistry Chemical Physics, Vol. 14, No. 39, 21.10.2012, p. 13569-13579.

Research output: Contribution to journalArticle

Clifton, Luke A. ; Sanders, Michael ; Kinane, Christian ; Arnold, Tom ; Edler, Karen J. ; Neylon, Cameron ; Green, Rebecca J. ; Frazier, Richard A. / The role of protein hydrophobicity in thionin–phospholipid interactions: a comparison of α1 and α2-purothionin adsorbed anionic phospholipid monolayers. In: Physical Chemistry Chemical Physics. 2012 ; Vol. 14, No. 39. pp. 13569-13579.
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