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 H-1, C-13, and N-15 r esonances of the PH domain from dynamin have been obtained from homonu clear and heteronuclear NMR experiments. The secondary structure has b een elucidated from the pattern of nuclear Overhauser enhancements, fr om C-13 chemical shift deviations, and from observation of slowly exch anging amide hydrogens. The secondary structure contains one alpha-hel ix and eight beta-strands, seven of which are arranged in two contiguo us, antiparallel beta-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 app arently flexible loops. Steady-state N-15{H-1} nuclear Overhauser effe ct measurements indicate unequivocally the boundaries of this PH domai n, and the structured portion of the domain appears to be more extende d to the C terminus than previously suggested for other PH domains.