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EnglishThe assembly of soluble proteins into ordered fibrillar aggregates with cross-beta structure is an essential event of many human diseases. The polypeptides undergoing aggregation are generally small in size. To explore if the small size is a primary determinant for the formation of amyloids under pathological conditions we have created two databases of proteins, forming amyloid-related and non-amyloid deposits in human diseases, respectively. The size distributions of the two protein populations are well separated, with the systems forming non-amyloid deposits appearing significantly larger. We have then investigated the propensity of the 486-residue hexokinase-B from Saccharomyces cerevisiae (YHKB) to form amyloid-like fibrils in vitro. This size is intermediate between the size distributions of amyloid and non-amyloid forming proteins. Aggregation was induced under conditions known to be most effective for amyloid formation by normally globular proteins: (i) low pH with salts, (ii) pH 5.5 with trifluoroethanol. In both situations YHKB aggregated very rapidly into species with significant beta-sheet structure, as detected using circular dichroism and X-ray diffraction, but a weak Thioflavin T and Congo red binding. Moreover, atomic force microscopy indicated a morphology distinct from typical amyloid fibrils. Both types of aggregates were cytotoxic to human neuroblastoma cells, as indicated by the MTT assay. This analysis indicates that large proteins have a high tendency to form toxic aggregates, but low propensity to form regular amyloid in vivo and that such a behavior is intrinsically determined by the size of the protein, as suggested by the in vitro analysis of our sample protein.
Large proteins have a great tendency to aggregate but a low propensity to form amyloid fibrils / H. Ramshini; C. Parrini; A. Relini; M. Zampagni; B. Mannini; A. Pesce; A. Akbar Saboury; M. Nemat-Gorgani; F. Chiti. - In: PLOS ONE. - ISSN 1932-6203. - ELETTRONICO. - 6(2011), pp. e16075-1-e16075-10.
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| Titolo: | Large proteins have a great tendency to aggregate but a low propensity to form amyloid fibrils |
| Autori: | |
| Data di pubblicazione: | 2011 |
| Rivista: | |
| Citazione: | Large proteins have a great tendency to aggregate but a low propensity to form amyloid fibrils / H. Ramshini; C. Parrini; A. Relini; M. Zampagni; B. Mannini; A. Pesce; A. Akbar Saboury; M. Nemat-Gorgani; F. Chiti. - In: PLOS ONE. - ISSN 1932-6203. - ELETTRONICO. - 6(2011), pp. e16075-1-e16075-10. |
| Abstract: | The assembly of soluble proteins into ordered fibrillar aggregates with cross-beta structure is an essential event of many human diseases. The polypeptides undergoing aggregation are generally small in size. To explore if the small size is a primary determinant for the formation of amyloids under pathological conditions we have created two databases of proteins, forming amyloid-related and non-amyloid deposits in human diseases, respectively. The size distributions of the two protein populations are well separated, with the systems forming non-amyloid deposits appearing significantly larger. We have then investigated the propensity of the 486-residue hexokinase-B from Saccharomyces cerevisiae (YHKB) to form amyloid-like fibrils in vitro. This size is intermediate between the size distributions of amyloid and non-amyloid forming proteins. Aggregation was induced under conditions known to be most effective for amyloid formation by normally globular proteins: (i) low pH with salts, (ii) pH 5.5 with trifluoroethanol. In both situations YHKB aggregated very rapidly into species with significant beta-sheet structure, as detected using circular dichroism and X-ray diffraction, but a weak Thioflavin T and Congo red binding. Moreover, atomic force microscopy indicated a morphology distinct from typical amyloid fibrils. Both types of aggregates were cytotoxic to human neuroblastoma cells, as indicated by the MTT assay. This analysis indicates that large proteins have a high tendency to form toxic aggregates, but low propensity to form regular amyloid in vivo and that such a behavior is intrinsically determined by the size of the protein, as suggested by the in vitro analysis of our sample protein. |
| Handle: | http://hdl.handle.net/11567/304059 |
| Appare nelle tipologie: | 01.01 - Articolo su rivista |
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