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Formation of amyloid fibrils via longitudinal growth of oligomers.

DIR@IMTECH: CSIR-Institute of Microbial Technology

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Title Formation of amyloid fibrils via longitudinal growth of oligomers.
 
Creator Shahi, Puja
Sharma, Ritu
Sanger, Shefali
Kumar, Ish
Jolly, R S
 
Subject QD Chemistry
 
Description Mature amyloid fibrils are believed to be formed by the lateral association of discrete structural units designated as protofibrils, but this lateral association of protofibrils has never been directly observed. We have recently characterized a thioesterase from Alcaligenes faecalis, which was shown to exist as homomeric oligomers with an average diameter of 21.6 nm consisting of 22 kDa subunits in predominantly beta-sheet structure. In this study, we have shown that upon incubation in a 75% ethanol solution, the oligomeric particles of protein were transformed into amyloid-like fibrils. TEM pictures obtained at various stages during fibril growth helped us to understand to a certain extent the early events in the fibrillization process. When incubated in 75% ethanol, oligomeric particles of protein grew to approximately 35-40 nm in diameter before fusion. Fusion of two oligomers of 35-40 nm resulted in the formation of a fibril. Fibril formation was accompanied by a reduction in the diameter of the particle to approximately 20-25 nm along with concomitant elongation to approximately 110 nm, indicating reorganization and strengthening of the structure. The elongation process continued by sequential addition of oligomeric units to give fibers 500-1000 nm in length with a further reduction in diameter to 17-20 nm. Further elongation resulted in the formation of fibers that were more than 4000 nm in length; the diameter, however, remained constant at 17-20 nm. These data clearly show that the mature fibrils have assembled via longitudinal growth of oligomers and not via lateral association of protofibrils.
 
Publisher ACS Publications
 
Date 2007-06-26
 
Type Article
PeerReviewed
 
Format application/pdf
 
Identifier http://crdd.osdd.net/open/635/2/bi7001136.pdf
Shahi, Puja and Sharma, Ritu and Sanger, Shefali and Kumar, Ish and Jolly, R S (2007) Formation of amyloid fibrils via longitudinal growth of oligomers. Biochemistry, 46 (25). pp. 7365-73. ISSN 0006-2960
 
Relation http://pubs.acs.org/doi/abs/10.1021/bi7001136
http://crdd.osdd.net/open/635/