title: Two-state conformational equilibrium in the Par-4 leucine zipper domain.
abstract: Prostate apoptosis response factor-4 (Par-4) is a pro-apoptotic and tumor-suppressive protein. A highly conserved heptad repeat sequence at the Par-4 C-terminus suggests the presence of a leucine zipper (LZ). This C-terminal region is essential for Par-4 self-association and interaction with various effector proteins. We have used nuclear magnetic resonance (NMR) spectroscopy to fully assign the chemical shift resonances of a peptide comprising the LZ domain of Par-4 at neutral pH. Further, we have investigated the properties of the Par-4 LZ domain and two point mutants under a variety of conditions using NMR, circular dichroism (CD), light scattering, and bioinformatics. Results indicate an environment-dependent conformational equilibrium between a partially ordered monomer (POM) and a predominantly coiled coil dimer (CCD). The combination of techniques used allows the time scales of the equilibrium to be probed and also helps to identify features of the amino acid sequence that may influence the equilibrium.
authors.affiliation: Centre for Structural Biology, Institute of Fundamental Sciences, Massey University, Palmerston North, New Zealand.
authors.forename: Martin
authors.initials: M
authors.lastname: Schwalbe
authors.forename: Kaushik
authors.initials: K
authors.lastname: Dutta
authors.forename: David S
authors.initials: DS
authors.lastname: Libich
authors.forename: Hariprasad
authors.initials: H
authors.lastname: Venugopal
authors.forename: Jolyon K
authors.initials: JK
authors.lastname: Claridge
authors.forename: David A
authors.initials: DA
authors.lastname: Gell
authors.forename: Joel P
authors.initials: JP
authors.lastname: Mackay
authors.forename: Patrick J B
authors.initials: PJ
authors.lastname: Edwards
authors.forename: Steven M
authors.initials: SM
authors.lastname: Pascal
mesh_terms: D051017:Apoptosis Regulatory Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D002850:Chromatography, Gel; D002942:Circular Dichroism; D004926:Escherichia coli / Q000235:genetics; D006863:Hydrogen-Ion Concentration; D016350:Leucine Zippers; D008027:Light; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D010455:Peptides / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011487:Protein Conformation; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012542:Scattering, Radiation; D013696:Temperature
chemical_list: D051017:Apoptosis Regulatory Proteins; D010455:Peptides; D011993:Recombinant Fusion Proteins; C101296:prostate apoptosis response-4 protein