Solution NMR structure of the barrier-to-autointegration factor-Emerin complex.
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.
Cai
Mengli
M
Laboratories of Chemical Physics and Molecular Biology, NIDDK, National Institutes of Health, Bethesda, MD 20892-0520, USA.
Huang
Ying
Y
Suh
Jeong-Yong
JY
Louis
John M
JM
Ghirlando
Rodolfo
R
Craigie
Robert
R
Clore
G Marius
GM
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
C501959:BANF1 protein, human; D004268:DNA-Binding Proteins; D008565:Membrane Proteins; D009687:Nuclear Proteins; D012996:Solutions; C092710:emerin