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Biochim Biophys Acta. 2016 Nov;1864(11):1489-99. doi: 10.1016/j.bbapap.2016.08.002. Epub 2016 Aug 6.

Structural model of amyloid fibrils for amyloidogenic peptide from Bgl2p-glucantransferase of S. cerevisiae cell wall and its modifying analog. New morphology of amyloid fibrils.

Author information

1
Institute of Protein Research, Russian Academy of Science, 142290 Pushchino, Moscow Region, Russia.
2
Institute of Protein Research, Russian Academy of Science, 142290 Pushchino, Moscow Region, Russia; Institute of Mathematical Problems of Biology RAS, Keldysh Institute of Applied Mathematics of Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia.
3
Branch of Federal State Budgetary Research Institution, "M.M. Shemyakin and Yu.A. Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences", Nauka Pr. 4, 142290 Pushchino, Moscow Region, Russia.
4
Department of Molecular Biology, Faculty of Biology, Moscow State University, Moscow, Russia.
5
Institute of Protein Research, Russian Academy of Science, 142290 Pushchino, Moscow Region, Russia; State Research Center for Applied Microbiology & Biotechnology, Obolensk, Serpukhov District, Moscow Region 142279, Russia.
6
Institute of Protein Research, Russian Academy of Science, 142290 Pushchino, Moscow Region, Russia. Electronic address: ogalzit@vega.protres.ru.

Abstract

We performed a comparative study of the process of amyloid formation by short homologous peptides with a substitution of aspartate for glutamate in position 2 - VDSWNVLVAG (AspNB) and VESWNVLVAG (GluNB) - with unblocked termini. Peptide AspNB (residues 166-175) corresponded to the predicted amyloidogenic region of the protein glucantransferase Bgl2 from the Saccharomyces cerevisiae cell wall. The process of amyloid formation was monitored by fluorescence spectroscopy (FS), electron microscopy (EM), tandem mass spectrometry (TMS), and X-ray diffraction (XD) methods. The experimental study at pH3.0 revealed formation of amyloid fibrils with similar morphology for both peptides. Moreover, we found that the morphology of fibrils made of untreated ammonia peptide is not mentioned in the literature. This morphology resembles snakes lying side by side in the form of a wave without intertwining. Irrespective of the way of the peptide preparation, the rate of fibril formation is higher for AspNB than for GluNB. However, preliminary treatment with ammonia highly affected fibril morphology especially for AspNB. Such treatment allowed us to obtain a lag period during the process of amyloid formation. It showed that the process was nucleation-dependent. With or without treatment, amyloid fibrils consisted of ring-like oligomers with the diameter of about 6nm packed either directly ring-to-ring or ring-on-ring with a slight shift. We also proposed the molecular structure of amyloid fibrils for two studied peptides.

KEYWORDS:

Amyloid fibrils; Amyloidogenic regions; Electron microscopy; Molecular structure; Oligomer; Tandem mass spectrometry; X-ray analysis

PMID:
27500912
DOI:
10.1016/j.bbapap.2016.08.002
[Indexed for MEDLINE]

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