title: Solution NMR structure of the barrier-to-autointegration factor-Emerin complex.
abstract: The barrier-to-autointegration factor BAF binds to the LEM domain (Em(LEM)) of the nuclear envelope protein emerin and plays an essential role in the nuclear architecture of metazoan cells. In addition, the BAF(2) dimer bridges and compacts double-stranded DNA nonspecifically via two symmetry-related DNA binding sites. In this article we present biophysical and structural studies on a complex of BAF(2) and Em(LEM). Light scattering, analytical ultracentrifugation, and NMR indicate a stoichiometry of one molecule of Em(LEM) bound per BAF(2) dimer. The equilibrium dissociation constant (K(d)) for the interaction of the BAF(2) dimer and Em(LEM), determined by isothermal titration calorimetry, is 0.59 +/- 0.03 microm. Z-exchange spectroscopy between corresponding cross-peaks of the magnetically non-equivalent subunits of the BAF(2) dimer in the complex yields a dissociation rate constant of 78 +/- 2s(-1). The solution NMR structure of the BAF(2)-Em(LEM) complex reveals that the LEM and DNA binding sites on BAF(2) are non-overlapping and that both subunits of the BAF(2) dimer contribute approximately equally to the Em(LEM) binding site. The relevance of the implications of the structural and biophysical data on the complex in the context of the interaction between the BAF(2) dimer and Em(LEM) at the nuclear envelope is discussed.
authors.affiliation: Laboratories of Chemical Physics and Molecular Biology, NIDDK, National Institutes of Health, Bethesda, MD 20892-0520, USA.
authors.forename: Mengli
authors.initials: M
authors.lastname: Cai
authors.forename: Ying
authors.initials: Y
authors.lastname: Huang
authors.forename: Jeong-Yong
authors.initials: JY
authors.lastname: Suh
authors.forename: John M
authors.initials: JM
authors.lastname: Louis
authors.forename: Rodolfo
authors.initials: R
authors.lastname: Ghirlando
authors.forename: Robert
authors.initials: R
authors.lastname: Craigie
authors.forename: G Marius
authors.initials: GM
authors.lastname: Clore
mesh_terms: D004268:DNA-Binding Proteins / Q000378:metabolism*; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D009685:Nuclear Envelope; D009687:Nuclear Proteins / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D012996:Solutions
chemical_list: C501959:BANF1 protein, human; D004268:DNA-Binding Proteins; D008565:Membrane Proteins; D009687:Nuclear Proteins; D012996:Solutions; C092710:emerin