Dissection of a beta-barrel motif leads to a functional dimer: The case of the intestinal fatty acid binding protein.

GISELA FRANCHINI; LUCRECIA M. CURTO; JULIO J. CARAMELO; JOSÉ MARÍA DELFINO

PROTEIN SCIENCE

Wiley Interscience

Año: 2009 vol. 18 p. 2592 - 2602

0961-8368

A lingering issue in the area of protein engineering is the optimal design of b motifs. In this regard, the framework provided by intestinal fatty acid binding protein (IFABP) was successfully chosen to explore the consequences on structure and function of the redesign of natural motifs. A truncated form of IFABP (D98D) served to illustrate the nonintuitive notion that the integrity of the b-barrel can indeed be compromised with no effect on the ability to attain a nativelike fold. This is most likely the outcome of the key role played by the pr servation of essential core residues. In the search for the minimal structural determinants of this fold, D98D offered room for further intervention. A dissection of this protein leads to a new abridged variant, D78D, containing 60% of the amino acids of IFABP. Spectroscopic analyses indicate that D78D retains substantial b-sheet content and preserves tertiary interactions, displaying cooperative unfolding and binding activity. Most strikingly, this construct adopts a remarkably stable dimeric structure in solution. This phenomenon takes advantage of the inherent structural plasticity of this motif, likely profitting from edge-to-edge interactions between b-sheets, whereas avoiding the most commonly occurring outcome represented by aggregation.b motifs. In this regard, the framework provided by intestinal fatty acid binding protein (IFABP) was successfully chosen to explore the consequences on structure and function of the redesign of natural motifs. A truncated form of IFABP (D98D) served to illustrate the nonintuitive notion that the integrity of the b-barrel can indeed be compromised with no effect on the ability to attain a nativelike fold. This is most likely the outcome of the key role played by the pr servation of essential core residues. In the search for the minimal structural determinants of this fold, D98D offered room for further intervention. A dissection of this protein leads to a new abridged variant, D78D, containing 60% of the amino acids of IFABP. Spectroscopic analyses indicate that D78D retains substantial b-sheet content and preserves tertiary interactions, displaying cooperative unfolding and binding activity. Most strikingly, this construct adopts a remarkably stable dimeric structure in solution. This phenomenon takes advantage of the inherent structural plasticity of this motif, likely profitting from edge-to-edge interactions between b-sheets, whereas avoiding the most commonly occurring outcome represented by aggregation.