Solution structure of pleckstrin homology domain of dynamin by heteronuclear NMR spectroscopy

The pleckstrin homology (PH) domain is a recognition motif thought to be involved in signal-transduction pathways controlled by a variety of cytoplasmic proteins. Assignments of nearly all ¹H, ¹³C, and ¹⁵N resonances of the PH domain from dynamin have been obtained from homonuclear and heteronuclear NMR experiments. The secondary structure has been elucidated from the pattern of nuclear Overhauser enhancements, from ¹³C chemical shift deviations, and from observation of slowly exchanging amide hydrogens. The secondary structure contains one α-helix and eight β- strands, seven of which are arranged in two contiguous, antiparallel β- sheets. The structure is monomeric, in contrast to the well-defined intimate dimerization of the crystal structure of this molecule. Residues possibly involved in ligand binding are in apparently flexible loops. Steady-state ¹⁵N{¹H} nuclear Overhauser effect measurements indicate unequivocally the boundaries of this PH domain, and the structured portion of the domain appears to be more extended to the C terminus than previously suggested for other PH domains.