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Morphological Transformations in the Magnetite Biomineralizing Protein Mms6 in Iron Solutions: A Small-Angle X-ray Scattering Study

TitleMorphological Transformations in the Magnetite Biomineralizing Protein Mms6 in Iron Solutions: A Small-Angle X-ray Scattering Study
Publication TypeJournal Article
Year of Publication2015
AuthorsZhang, HH, Liu, XP, Feng, SR, Wang, WJ, Schmidt-Rohr, K, Akinc, M, Nilsen-Hamilton, M, Vaknin, D, Mallapragada, S
JournalLangmuir
Volume31
Pagination2818-2825
Date Published03
Type of ArticleArticle
ISBN Number0743-7463
Accession NumberWOS:000350918500025
Keywordsbiology, crystal, magnetotactic bacteria, model, nanocrystals, nanoscale, nanostructures, oxide nanoparticles, systems
Abstract

Magnetotactic bacteria that produce magnetic nanocrystals of uniform size and well-defined morphologies have inspired the use of biomineralization protein Mms6 to promote formation of uniform magnetic nanocrystals in vitro. Small angle X-ray scattering (SAXS) studies in physiological solutions reveal that Mms6 forms compact globular three-dimensional (3D) micelles (approximately 10 nm in diameter) that are, to a large extent, independent of concentration. In the presence of iron ions in the solutions, the general micellar morphology is preserved, however, with associations among micelles that are induced by iron ions. Compared with Mms6, the m2Mms6 mutant (with the sequence of hydroxyl/carboxyl containing residues in the C-terminal domain shuffled) exhibits subtle morphological changes in the presence of iron ions in solutions. The analysis of the SAXS data is consistent with a hierarchical core-corona micellar structure similar to that found in amphiphilic polymers. The addition of ferric and ferrous iron ions to the protein solution induces morphological changes in the micellar structure by transforming the 3D micelles into objects of reduced dimensionality of 2, with fractal-like characteristics (including Gaussian-chain-like) or, alternatively, platelet-like structures.

DOI10.1021/la5044377
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Bioinspired Materials