Crystal packing interaction that blocks crystallization of a site-specificDNA binding protein-DNA complex

Littlefield, O Nelson, HCM

O. Littlefield et Hcm. Nelson, Crystal packing interaction that blocks crystallization of a site-specificDNA binding protein-DNA complex, PROTEINS, 45(3), 2001, pp. 219-228

34

INGLESE

Article

Biochemistry & Biophysics

PROTEINS-STRUCTURE FUNCTION AND GENETICS

0887-3585 → ACNP

45

3

2001

219 - 228

ISI

0887-3585(20011115)45:3<219:CPITBC>2.0.ZU;2-4

We present here three high-resolution crystal structures of complexes betwe en the DNA-binding domain of the heat-shock transcription factor (HSF) and DNA oligomers. Although the DNA oligomers contain HSF's specific binding se quence, called a heat-shock element, the crystal structures do not contain the specific protein-DNA complex. In one crystal structure, the 10 base pai r DNA oligomer is statically disordered. In the other two related structure s, the 12 base pair DNA oligomers are in unique positions, but the protein- DNA contacts in these two crystals are not sequence specific. In all three structures, the DNA appears to act as a rigid, polyanion scaffold to suppor t columns of proteins in a crystalline lattice. A robust crystal packing in terface between protein monomers obscures the true DNA-binding surface, kno wn from previous genetic and biochemical studies. By redesigning the protei n to interfere with the crystal lattice contacts, we were able to obtain ph ysiologically relevant crystals in a specific protein-DNA complex. Thus, a crystal-packing interface was able to prevent the weak, but physiological r elevant interactions between a protein and DNA. (C) 2001 Wiley-Liss, Inc.