title: Morphological transformations in the magnetite biomineralizing protein Mms6 in iron solutions: a small-angle X-ray scattering study.
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.
authors: Division of Materials Science and Engineering, Ames Laboratory, USDOE , Ames, Iowa 50011, United States.
authors: Honghu
authors: H
authors: Zhang
authors: Xunpei
authors: X
authors: Liu
authors: Shuren
authors: S
authors: Feng
authors: Wenjie
authors: W
authors: Wang
authors: Klaus
authors: K
authors: Schmidt-Rohr
authors: Mufit
authors: M
authors: Akinc
authors: Marit
authors: M
authors: Nilsen-Hamilton
authors: David
authors: D
authors: Vaknin
authors: Surya
authors: S
authors: Mallapragada
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism*; D007501:Iron / Q000737:chemistry*; D058185:Magnetite Nanoparticles / Q000737:chemistry*; D042201:Magnetospirillum; D008823:Micelles; D008903:Minerals / Q000378:metabolism*; D053838:Scattering, Small Angle; D012996:Solutions; D014961:X-Ray Diffraction
chemical_list: D001426:Bacterial Proteins; D058185:Magnetite Nanoparticles; D008823:Micelles; D008903:Minerals; D012996:Solutions; D007501:Iron