Sandbox Reserved 959
From Proteopedia
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| - | [[Image: disulfure.jpg|350px|left|thumb| Defensin-Alpha-1 cysteine connectivities.<ref>Stephen H Wile, William C Wimley and Michael E Selsted. Structure, function, and membrane integration of defensins. Current Opinion in Structural Biology 1995. University of California, Irvine, USA</ref>]] | + | [[Image: disulfure.jpg|350px|left|thumb| Defensin-Alpha-1 cysteine connectivities.<ref name="stephen">Stephen H Wile, William C Wimley and Michael E Selsted. Structure, function, and membrane integration of defensins. Current Opinion in Structural Biology 1995. University of California, Irvine, USA</ref>]] |
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=== Dimere structure === | === Dimere structure === | ||
| - | The dimere is formed by joining identical β-strands of the two monomers together to create a symmetrical six-stranded β-sheet. This extended β-sheet twists and curls to form a basket-shaped structure that has a small solvent-accessible channel passing through it. The base of the basket is hydrophobic while the top, which contains the N- and C-terminal domains of the two defensin monomers, is polar. This dimer-of-dimers may be an essential feature of defensins’interaction with membranes.<ref>Gary Fujii, Michael E.Selsted, David Eisenberg. Defensins promote fusion and lysis of negatively charged membranes. Protein Science. 1993. Cambridge University</ref> | + | The dimere is formed by joining identical β-strands of the two monomers together to create a symmetrical six-stranded β-sheet. This extended β-sheet twists and curls to form a basket-shaped structure that has a small solvent-accessible channel passing through it. The base of the basket is hydrophobic while the top, which contains the N- and C-terminal domains of the two defensin monomers, is polar. This dimer-of-dimers may be an essential feature of defensins’interaction with membranes.<ref name="gary">Gary Fujii, Michael E.Selsted, David Eisenberg. Defensins promote fusion and lysis of negatively charged membranes. Protein Science. 1993. Cambridge University</ref> |
=== Binding with the cell membrane === | === Binding with the cell membrane === | ||
The interaction of defensin-α-1 with cell membranes involves single dimer binding electrostatically to the cell surface. | The interaction of defensin-α-1 with cell membranes involves single dimer binding electrostatically to the cell surface. | ||
In fact, the hydrophobic basket bottom of the defensin-α-1 dimer is inserted into the the hydrocarbon layer of one lipid monolayer while the polar group of the basket top and the <scene name='60/604478/Arg/1'>arginine</scene> maintain contact with the headgroup and aqueaus phase. Two dimers created a channel. | In fact, the hydrophobic basket bottom of the defensin-α-1 dimer is inserted into the the hydrocarbon layer of one lipid monolayer while the polar group of the basket top and the <scene name='60/604478/Arg/1'>arginine</scene> maintain contact with the headgroup and aqueaus phase. Two dimers created a channel. | ||
| - | The dimers can work together and create big channels like the following picture. The <scene name='60/604478/Hydrophobe/1'>hydrophobic residues</scene> are in the basket bottom.<ref | + | The dimers can work together and create big channels like the following picture. The <scene name='60/604478/Hydrophobe/1'>hydrophobic residues</scene> are in the basket bottom.<ref name = "stephen"/> |
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| - | [[Image: membrane.jpg|350px|left|thumb|Creation of big channels.<ref | + | [[Image: membrane.jpg|350px|left|thumb|Creation of big channels..<ref name = "gary"/>]] ]] |
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Revision as of 20:34, 8 January 2015
| This Sandbox is Reserved from 06/12/2018, through 30/06/2019 for use in the course "Structural Biology" taught by Bruno Kieffer at the University of Strasbourg, ESBS. This reservation includes Sandbox Reserved 1480 through Sandbox Reserved 1543. |
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Defensins-α-1
Introduction
Defensins (DEF) are a family of proteins which are involved in host defense in the epithelia of mucosal surfaces such as those of the intestin, respiratory tract, urinary tract, and vagina. They are antimicrobial and cytotoxic. All the protein of the family are distinguished by a cystein motif and are encoded on the chromozome 8.[1]
There are many defensin but in this article we'll focus on the defensin-α-1. It is a polypeptide which is found in the microbicidal granules of neutrophils. It's syntetisize in the neutrophils, which plays a role in the defense process. defensin-α-1 plays a particular role in phagocite-mediated host defense.[2]
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