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Amyloidogenic properties of a D/N mutated 12 amino acid fragment of the C-terminal domain of the Cholesteryl-Ester Transfer Protein (CETP).

García-González V, Mas-Oliva J - Int J Mol Sci (2011)

Bottom Line: Using a series of peptides derived from this C-terminal domain, the present study shows that these changes favor the induction of a secondary β-structure as characterized by spectroscopic analysis and fluorescence techniques.Therefore, a fine balance between the highly dynamic secondary structure of the C-terminal domain of CETP, the net charge, and the physicochemical characteristics of the surrounding microenvironment define the type of secondary structure acquired.Changes in this balance might favor misfolding in this region, which would alter the lipid transfer capacity conducted by CETP, favoring its propensity to substitute its physiological function.

View Article: PubMed Central - PubMed

Affiliation: Institute of Cell Physiology, National Autonomus University of Mexico (UNAM), AP 70-243, 04510 Mexico, D.F., Mexico; E-Mail: vgarcia@emailifc.unam.mx.

ABSTRACT
The cholesteryl-ester transfer protein (CETP) facilitates the transfer of cholesterol esters and triglycerides between lipoproteins in plasma where the critical site for its function is situated in the C-terminal domain. Our group has previously shown that this domain presents conformational changes in a non-lipid environment when the mutation D(470)N is introduced. Using a series of peptides derived from this C-terminal domain, the present study shows that these changes favor the induction of a secondary β-structure as characterized by spectroscopic analysis and fluorescence techniques. From this type of secondary structure, the formation of peptide aggregates and fibrillar structures with amyloid characteristics induced cytotoxicity in microglial cells in culture. These supramolecular structures promote cell cytotoxicity through the formation of reactive oxygen species (ROS) and change the balance of a series of proteins that control the process of endocytosis, similar to that observed when β-amyloid fibrils are employed. Therefore, a fine balance between the highly dynamic secondary structure of the C-terminal domain of CETP, the net charge, and the physicochemical characteristics of the surrounding microenvironment define the type of secondary structure acquired. Changes in this balance might favor misfolding in this region, which would alter the lipid transfer capacity conducted by CETP, favoring its propensity to substitute its physiological function.

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Related in: MedlinePlus

Model of an antiparallel β-strand in helix-Z. (A) The charge of each residue is determined considering a pH of 7.2. N and C terminal groups are loaded allowing an electrostatic attraction between peptide chains. Shaded regions identify the hydrophobic cluster L467LVNFL472, as well as N and Q residues; (B) Helix-X does not form a β-strand structure due to the electrostatic repulsion between D residues.
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f8-ijms-12-02019: Model of an antiparallel β-strand in helix-Z. (A) The charge of each residue is determined considering a pH of 7.2. N and C terminal groups are loaded allowing an electrostatic attraction between peptide chains. Shaded regions identify the hydrophobic cluster L467LVNFL472, as well as N and Q residues; (B) Helix-X does not form a β-strand structure due to the electrostatic repulsion between D residues.

Mentions: Taking into account the spectrophotometric results, the evidence of fibrillar structures and the physicochemical properties of helix-Z such as μH, hydrophobicity, and a net charge of −0.96 at pH 7.2, we present a model for the amino acid residue disposition within the β-strand (Figure 8A). Since D470N showed the loss of one negative charge, the hydrophobic cluster (L467LVNFL472) maintained a β-conformation through hydrophobic interactions. It is also important to consider that along the sequence, there are asparagine and glutamine residues that are considered as inducers of β-structures and therefore allow the stacking of polypeptide chains [27]. Helix-X does not show this phenomenon, largely due to an electrostatic repulsion at Asp-470 that prevents the formation of a hydrophobic cluster that maintains the peptide under an extended state (Figure 8B).


Amyloidogenic properties of a D/N mutated 12 amino acid fragment of the C-terminal domain of the Cholesteryl-Ester Transfer Protein (CETP).

García-González V, Mas-Oliva J - Int J Mol Sci (2011)

Model of an antiparallel β-strand in helix-Z. (A) The charge of each residue is determined considering a pH of 7.2. N and C terminal groups are loaded allowing an electrostatic attraction between peptide chains. Shaded regions identify the hydrophobic cluster L467LVNFL472, as well as N and Q residues; (B) Helix-X does not form a β-strand structure due to the electrostatic repulsion between D residues.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC3111648&req=5

f8-ijms-12-02019: Model of an antiparallel β-strand in helix-Z. (A) The charge of each residue is determined considering a pH of 7.2. N and C terminal groups are loaded allowing an electrostatic attraction between peptide chains. Shaded regions identify the hydrophobic cluster L467LVNFL472, as well as N and Q residues; (B) Helix-X does not form a β-strand structure due to the electrostatic repulsion between D residues.
Mentions: Taking into account the spectrophotometric results, the evidence of fibrillar structures and the physicochemical properties of helix-Z such as μH, hydrophobicity, and a net charge of −0.96 at pH 7.2, we present a model for the amino acid residue disposition within the β-strand (Figure 8A). Since D470N showed the loss of one negative charge, the hydrophobic cluster (L467LVNFL472) maintained a β-conformation through hydrophobic interactions. It is also important to consider that along the sequence, there are asparagine and glutamine residues that are considered as inducers of β-structures and therefore allow the stacking of polypeptide chains [27]. Helix-X does not show this phenomenon, largely due to an electrostatic repulsion at Asp-470 that prevents the formation of a hydrophobic cluster that maintains the peptide under an extended state (Figure 8B).

Bottom Line: Using a series of peptides derived from this C-terminal domain, the present study shows that these changes favor the induction of a secondary β-structure as characterized by spectroscopic analysis and fluorescence techniques.Therefore, a fine balance between the highly dynamic secondary structure of the C-terminal domain of CETP, the net charge, and the physicochemical characteristics of the surrounding microenvironment define the type of secondary structure acquired.Changes in this balance might favor misfolding in this region, which would alter the lipid transfer capacity conducted by CETP, favoring its propensity to substitute its physiological function.

View Article: PubMed Central - PubMed

Affiliation: Institute of Cell Physiology, National Autonomus University of Mexico (UNAM), AP 70-243, 04510 Mexico, D.F., Mexico; E-Mail: vgarcia@emailifc.unam.mx.

ABSTRACT
The cholesteryl-ester transfer protein (CETP) facilitates the transfer of cholesterol esters and triglycerides between lipoproteins in plasma where the critical site for its function is situated in the C-terminal domain. Our group has previously shown that this domain presents conformational changes in a non-lipid environment when the mutation D(470)N is introduced. Using a series of peptides derived from this C-terminal domain, the present study shows that these changes favor the induction of a secondary β-structure as characterized by spectroscopic analysis and fluorescence techniques. From this type of secondary structure, the formation of peptide aggregates and fibrillar structures with amyloid characteristics induced cytotoxicity in microglial cells in culture. These supramolecular structures promote cell cytotoxicity through the formation of reactive oxygen species (ROS) and change the balance of a series of proteins that control the process of endocytosis, similar to that observed when β-amyloid fibrils are employed. Therefore, a fine balance between the highly dynamic secondary structure of the C-terminal domain of CETP, the net charge, and the physicochemical characteristics of the surrounding microenvironment define the type of secondary structure acquired. Changes in this balance might favor misfolding in this region, which would alter the lipid transfer capacity conducted by CETP, favoring its propensity to substitute its physiological function.

Show MeSH
Related in: MedlinePlus