title: Narrowing the conformational space sampled by two-domain proteins with paramagnetic probes in both domains.
abstract: Calmodulin is a two-domain protein which in solution can adopt a variety of conformations upon reorientation of its domains. The maximum occurrence (MO) of a set of calmodulin conformations that are representative of the overall conformational space possibly sampled by the protein, has been calculated from the paramagnetism-based restraints. These restraints were measured after inclusion of a lanthanide binding tag in the C-terminal domain to supplement the data obtained by substitution of three paramagnetic lanthanide ions to the calcium ion in the second calcium binding loop of the N-terminal domain. The analysis shows that the availability of paramagnetic restraints arising from metal ions placed on both domains, reduces the MO of the conformations to different extents, thereby helping to identify those conformations that can be mostly sampled by the protein.
authors.affiliation: Magnetic Resonance Center (CERM), University of Florence, Via Luigi Sacconi 6, 50019 Sesto Fiorentino, Italy.
authors.forename: Soumyasri
authors.initials: S
authors.lastname: Dasgupta
authors.forename: Xiaoyu
authors.initials: X
authors.lastname: Hu
authors.forename: Peter H J
authors.initials: PH
authors.lastname: Keizers
authors.forename: Wei-Min
authors.initials: WM
authors.lastname: Liu
authors.forename: Claudio
authors.initials: C
authors.lastname: Luchinat
authors.forename: Malini
authors.initials: M
authors.lastname: Nagulapalli
authors.forename: Mark
authors.initials: M
authors.lastname: Overhand
authors.forename: Giacomo
authors.initials: G
authors.lastname: Parigi
authors.forename: Luca
authors.initials: L
authors.lastname: Sgheri
authors.forename: Marcellus
authors.initials: M
authors.lastname: Ubbink
mesh_terms: D001665:Binding Sites; D002118:Calcium / Q000737:chemistry; D002147:Calmodulin / Q000737:chemistry* / Q000378:metabolism; D004578:Electron Spin Resonance Spectroscopy; D028581:Lanthanoid Series Elements; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D017434:Protein Structure, Tertiary
chemical_list: D002147:Calmodulin; D028581:Lanthanoid Series Elements; D002118:Calcium