NMR DERIVED INSIGHTS INTO THE CONFORMATIONAL CHANGES EXERTED BY TFE ON THE IFABP ABRIDGED FAMILY

CURTO L.M.; ANGELANI, C.R.; ARÁN, M.; GALLO, M.; DELFINO J.M.

Congreso; XLIII Reunión Anual de la Sociedad Argentina de Biofísica; 2014

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 2 perpendicular 5-stranded β-sheets and an intervening helix-turn-helix 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.