Effects of pH on aggregation kinetics of the repeat domain of a functional amyloid, Pmel17

• DOI: 10.1073/pnas.1006424107
• Publication Date: 2010-11-25T03:52:28Z
• Authors: Candace M. Pfeffe...; Ryan P. McGlinchey; Jennifer C. Lee
• Keywords: Amyloid (mycology)

Pmel17 is a functional amyloidogenic protein whose fibrils act as scaffolds for pigment deposition in human skin and eyes. We have used the repeat domain (RPT, residues 315-444), an essential luminal polypeptide region of Pmel17, model system to study conformational changes from soluble unstructured monomers β-sheet-containing fibrils. Specifically, we report on effects solution pH (4 → 7) mimicking conditions melanosomes, acidic organelles where are formed. Local, secondary, fibril structure were monitored via intrinsic Trp fluorescence, circular dichroism spectroscopy, transmission electron microscopy, respectively. find that W423 highly sensitive probe amyloid assembly with spectral features reflecting local morphological changes. A critical regime (5 ± 0.5) was identified formation suggesting involvement at least three carboxylic acids structural rearrangement necessary aggregation. Moreover, demonstrate RPT morphology can be transformed directly by changing pH. Based these results, propose intramelanosomal regulates its subsequent dissolution vivo.