Identification of a human estrogen receptor alpha-derived antiestrogenic peptide that adopts a polyproline II conformation.
Polyproline II (PPII) helix is an extended secondary structure present in a number of proteins. PPII-containing sequences mediate specific protein-protein interactions with partners containing appropriate cognate domains called PPII-recognizing domains (PRDs) and are involved in the activation of intracellular signaling pathways. Thus, the identification of PPII structures in proteins is of great interest, not only to explore molecular and physiological mechanisms, but also to elaborate new potential drugs. By revisiting X-ray crystal structures of liganded alpha-type human estrogen receptor (ERalpha), we have identified an 11-residue PPII-helical sequence (D(321)AEPPILYSEY(331)) in the ligand-binding domain of the receptor. The data recorded by far-ultraviolet circular dichroism (far-UV CD), vibrational Raman optical activity (ROA) and differential scanning calorimetry (DSC) show that the corresponding peptide (Ac-DAEPPILYSEY-NH(2)) is particularly well structured in PPII, with the same proportion of PPII as observed from X-ray structures (approximately 85%). In addition, studies carried out on ERalpha-negative Evsa-T breast cancer cells transiently co-transfected with a pcDNA3-ERalpha plasmid and a Vit-tk-Luc reporter gene revealed that the peptide antagonizes the estradiol-induced transcription providing perspectives for researching new molecules with antagonistic properties.
WestCHEM, Department of Chemistry, University of Glasgow, Glasgow G12 8QQ, UK.
Josef
J
Kapitán
Dominique
D
Gallo
Nicole
N
Goasdoué
Magali
M
Nicaise
Michel
M
Desmadril
Lutz
L
Hecht
Guy
G
Leclercq
Laurence D
LD
Barron
Yves
Y
Jacquot
D000595:Amino Acid Sequence; D045744:Cell Line, Tumor; D002942:Circular Dichroism; D020847:Estrogen Receptor Modulators / Q000737:chemistry*; D047628:Estrogen Receptor alpha / Q000737:chemistry*; D006801:Humans; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry*; D011487:Protein Conformation
D020847:Estrogen Receptor Modulators; D047628:Estrogen Receptor alpha; D010455:Peptides; C011083:polyproline