title: Structure of the C-terminal domain of the pro-apoptotic protein Hrk and its interaction with model membranes.
abstract: The protein harakiri (Hrk) is a pro-apoptotic BH3-only protein which belongs to the Bcl-2 family. Hrk appears associated to the mitochondrial outer membrane, apparently by a putative transmembrane domain, where it exerts its function. In this work we have identified a 27mer peptide supposed to be the putative membrane domain of the protein at the C-terminal region, and used infrared and fluorescence spectroscopies to study its secondary structure as well as to characterize its effect on the physical properties of phospholipid model membranes. The results presented here showed that the C-terminal region of Hrk adopts a predominantly alpha-helical structure whose proportion and destabilization capability varied depending on phospholipid composition. Moreover it was found that the orientation of the alpha-helical component of this C-terminal Hrk peptide was nearly perpendicular to the plane of the membrane. These results indicate that this domain is able of inserting into membranes, where it adopts a transmembrane alpha-helical structure as well as it considerably perturbs the physical properties of the membrane.
authors: Instituto de Biología Molecular y Celular, Edf. Torregaitán, Campus de Elche, Universidad Miguel Hernández, Elche, Alicante, Spain.
authors: Angela
authors: A
authors: Bernabeu
authors: Jaime
authors: J
authors: Guillén
authors: Ana J
authors: AJ
authors: Pérez-Berná
authors: Miguel R
authors: MR
authors: Moreno
authors: José
authors: J
authors: Villalaín
mesh_terms: D000595:Amino Acid Sequence; D051017:Apoptosis Regulatory Proteins / Q000235:genetics* / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D010455:Peptides / Q000138:chemical synthesis / Q000235:genetics*; D010743:Phospholipids / Q000737:chemistry; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D013050:Spectrometry, Fluorescence; D013055:Spectrophotometry, Infrared
chemical_list: D051017:Apoptosis Regulatory Proteins; C484586:HRK protein, human; D008565:Membrane Proteins; D010455:Peptides; D010743:Phospholipids