The yeast prion [PSI+] provides a powerful system to investigate the molecular basis of prion inheritance. The [PSI+] phenotype results form self-propagating aggregates of an essential translation termination factor, the protein Sup35 that leads to a nonsense suppression phenotype. In a recent study using extrinsic fluorophores attached along to the Sup35 sequence, Lindquist et al were able to map the regions of the protein that are protected or exposed in the fibril. However, the position of the region around residues 110-121 was inconclusive. Thus, we constructed a F117W mutant of Sup35 to have and intrinsic probe around this region to be used in aggregation experiments. When aggregation of F117W Sup35 was performed at 25 ºC, the fluorescence emission of Trp117 suggests that the region around position 117 is partially protected form the solvent. However, when aggregation was performed at 4 ºC, Trp117 remains solvent exposed. These data suggest that the amyloid fibril of Sup35 can adopt distinct conformation depending on the temperature where they grow. In fact, it has been suggested that 4 ºC grown fibrils are much more unstructured that the 25 ºC fibril, and indeed, circular dichroism measurements sowed that the secondary structure content of the later is higher. Thermodenaturation experiments followed by electrophoresis showed also that the fibrils grown at 4 ºC are more unstable that the one grown at 25 ºC. Regarding the tinctorial properties of these two types of fibrils, we observed that both fibrils bind equal amount of Congo red but, the fibril grown at 25 ºC bind 1.5 fold more thioflavin T that the 4 ºC fibril. Curiously, when these two types of fibers were subjected to the perturbing agent, high hydrostatic pressure, instead of being dissociate, they were converted into a new more ordered structure able to bind twice the amount of thioflavin T compared to atmospheric pressure. These results suggest that the amyloid fold, in principle, can assume at least two distinct conformations. The physiological relevance of these two conformations has to be investigated.  Financial support: CNPq.