NMR derived insights into the conformational changes exerted by TFE on the IFABP abridged family.

LM CURTO, CR ANGELANI, M ARÁN, M GALLO, JM DELFINO

Sierra de la Ventana, Buenos Aires

Congreso; XLIII Reunión Anual de SAB; 2014

SAB

IFABP (intestinal fatty acid binding protein) is a 15 kDa intracellular lipid binding protein that represents an excellent model of study for β-barrel proteins. It exhibits a β-clam structure built of 2perpendicular 5-stranded β-sheets and an intervening helix-turnhelix motif located in between strands A and B. Δ98Δ (fragment 29-126) is a monomeric all-β sheet variant that lacks β-strand A, most of the helical domain and the last 5 C-terminal amino acids. By contrast, a further abridged form, Δ78Δ (fragment 29-106) adopts a stable dimeric structure. Albeit displaying increased conformational plasticity, these variants exhibit a β-barrel topology and are able to support a cooperative folding behavior. Despite the putative exposure of free edges, the constructs are stable in solution and lack any intrinsic trend to aggregate. We have postulated that these variants share a compact core decorated by a loose peripheral region. Here we show preliminary NMR results on the influence of the co-solvent 2,2,2-trifluoroethanol (TFE, up to 10%v/v) that support a gain of structure. Changes observed go in line with the global consolidation of a  native-like topology, as evidenced by circular dichroism spectroscopy in both the far and near UV regions.