Near-UV circular dichroism reveals structural transitions of vimentin subunits during intermediate filament assembly

Georgakopoulou, Sofia and Möller, Dorothee and Sachs, Nadine and Herrmann, Harald and Aebi, Ueli. (2009) Near-UV circular dichroism reveals structural transitions of vimentin subunits during intermediate filament assembly. Journal of molecular biology, Vol. 386, H. 2. pp. 544-553.

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Official URL: http://edoc.unibas.ch/dok/A5265314

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In vitro assembly of vimentin intermediate filaments (IFs) proceeds from soluble, reconstituted tetrameric complexes to mature filaments in three distinct stages: (1) within the first seconds after initiation of assembly, tetramers laterally associate into unit-length filaments (ULFs), on average 17 nm wide; (2) for the next few minutes, ULFs grow by longitudinal annealing into short, immature filaments; (3) almost concomitant with elongation, these immature filaments begin to radially compact, yielding approximately 11-nm-wide IFs at around 15 min. The near-UV CD signal of soluble tetramers exhibits two main peaks at 285 and 278 nm, which do not change during ULF formation. In contrast, the CD signal of mature IFs exhibits two major changes: (1) the 278-nm band, denoting the transition of the tyrosines from the ground state to the first vibrational mode of the excited state, is lost; (2) a red-shifted band appears at 291 nm, indicating the emergence of a new electronic species. These changes take place independently and at different time scales. The 278-nm signal disappears within the first minute of assembly, compatible with increased rigidity of the tyrosines during elongation of the ULFs. The rise of the 291-nm band has a lifetime of approximately 13 min and denotes the generation of phenolates by deprotonation of the tyrosines' hydroxyl group after they relocalize into a negatively charged environment. The appearance of such tyrosine-binding "pockets" in the assembling filaments highlights an essential part of the molecular rearrangements characterizing the later stages of the assembly process, including the radial compaction.
Faculties and Departments:05 Faculty of Science > Departement Biozentrum > Former Organization Units Biozentrum > Structural Biology (Aebi)
UniBasel Contributors:Aebi, Ueli
Item Type:Article, refereed
Article Subtype:Research Article
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:22 Mar 2012 14:22
Deposited On:22 Mar 2012 13:28

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