Conversion of yeast phosphoglycerate kinase into amyloid-like structure

Abstract

Yeast phosphoglycerate kinase is a structurally well-characterized enzyme consisting of 415 amino acids without disulfide bonds. Anion-induced refolding from its acid-unfolded state gives rise to the formation of worm-like amyloid fibrils with a persistence length of 73 nm. Electron microscopy and small-angle X-ray scattering data indicate that the fibrils have an elliptical cross-section with dimensions of 10.2 nm x 5.1 nm. About half of all amino acids are organized in form of cross-beta structure which gives rise to typical infrared spectra, X-ray diffraction and yellow-green birefringence after Congo red staining. The kinetics of amyloid formation, monitored by infrared spectroscopy, dynamic light scattering and X-ray scattering, was found to be strongly dependent on protein concentration. The infrared data indicate that the formation of cross-beta structure practically comes to an end already after some hours, whereas the length-growth of the amyloid fibrils, monitored by small-angle X-ray scattering, was not yet completed after 1,300 hours.

Conformational Intermediate of the Amyloidogenic Protein β2-Microglobulin at Neutral pH

“…The results together with the outcome of far-UV circular dichroism measurements support the conclusion that ␤ 2 m in 40 -50% acetonitrile and 25-35% TFE forms a partially structured intermediate or a distinctly different conformation that binds CR more strongly than the native form and precipitates out of solution over time. Transient intermediates of proteins with less ␤-structure and more ␣-helix have also been found in other studies of amyloid disease-related and unrelated proteins (10,36,37,42), and it has been suggested that a defined ␣-helix content in partially structured intermediates may favor the further transition to ␤-sheets and amyloid fibrillation (39,43).…”

“…In a number of cases, amyloid fibril formation from these disease-associated proteins has been shown to be initiated in vitro under conditions that stabilize partially unfolded soluble intermediates of the native proteins (3,5,6,35,36). A growing list of additional proteins and peptides, including de novo designed synthetic proteins without known amyloid disease association, may also form amyloid fibrils in vitro under similar conditions (10,12,13,37,38). Amyloid fibrils consist of stable and insoluble assemblies of proteins in stacked ␤-sheets (39).…”

Protein folding revisited. A polypeptide chain at the folding ? misfolding ? nonfolding cross-roads: which way to go?

“…Fig. 4 compares parameters of far-ultraviolet (UV) circular dichroism (CD) spectra measured for 'pure' amyloidogenic conformations of 11 proteins (SH3 domain [98], cytocrome c 552 [110], monellin [100], methionine aminopeptidase [106], SMA [138], a-lactalbumin [115], phosphoglycerate kinase, PGK [105], amylin [93], prothymosin a [114], Ab [151] and a-synuclein [97]), with those retrieved for the four basic protein conformations, native, molten globule, premolten globule and unfolded states. In this plot data for the premolten globule and unfolded states are taken from [11], and the data for molten globules are from [154].…”

Tryptophanyl Substitutions in Apomyoglobin Determine Protein Aggregation and Amyloid-like Fibril Formation at Physiological pH

“…Electron microscopy shows that the fibrils are straight and unbranched and are 40 -120 Å in diameter (9,10). Also proteins not known to be associated with amyloid disease may form amyloid fibrils under in vitro conditions that favor partially folded states (11)(12)(13)(14)(15). These states are more prone to aggregation than the native state because hydrophobic residues, which are largely buried within the core of the native protein, become more exposed upon partial unfolding.…”