The Morphology of Decorated Amyloid Fibers is Controlled by the Conformation and Position of the Displayed Protein

Self-assembled structures capable of mediating electron transfer are an attractive scientific and technological goal. Therefore, systematic variants of SH3-Cytochrome b 562 fusion proteins were designed to make amyloid fibers displaying heme-b 562 electron transfer complexes. TEM and AFM data show t...

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Bibliographic Details
Published in:ACS nano 2012-02, Vol.6 (2), p.1332-1346
Main Authors: Forman, Christopher J, Nickson, Adrian A, Anthony-Cahill, Spencer J, Baldwin, Andrew J, Kaggwa, Gillian, Feber, Urs, Sheikh, Khizar, Jarvis, Suzanne P, Barker, Paul D
Format: Article
Language:English
Subjects:
Amyloid - chemistry
Amyloid - metabolism
Atomic force microscopy
Cytochrome b Group - chemistry
Cytochrome b Group - metabolism
Electron transfer
Electron Transport
Fibers
Heme - metabolism
Imaging
Mathematical morphology
Microscopy, Atomic Force
Models, Molecular
Modulation
Morphology
Nanostructure
Protein Multimerization
Proteins
Recombinant Fusion Proteins - chemistry
Recombinant Fusion Proteins - metabolism
src Homology Domains
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Summary:Self-assembled structures capable of mediating electron transfer are an attractive scientific and technological goal. Therefore, systematic variants of SH3-Cytochrome b 562 fusion proteins were designed to make amyloid fibers displaying heme-b 562 electron transfer complexes. TEM and AFM data show that fiber morphology responds systematically to placement of b 562 within the fusion proteins. UV–vis spectroscopy shows that, for the fusion proteins under test, only half the fiber-borne b 562 binds heme with high affinity. Cofactor binding also improves the AFM imaging properties and changes the fiber morphology through changes in cytochrome conformation. Systematic observations and measurements of fiber geometry suggest that longitudinal registry of subfilaments within the fiber, mediated by the interaction and conformation of the displayed proteins and their interaction with surfaces, gives rise to the observed morphologies, including defects and kinks. Of most interest is the role of small molecule modulation of fiber structure and mechanical stability. A minimum complexity model is proposed to capture and explain the fiber morphology in the light of these results. Understanding the complex interplay between these factors will enable a fiber design that supports longitudinal electron transfer.
ISSN:1936-0851
1936-086X
DOI:10.1021/nn204140a