Self-Assembly and Biphasic Iron-Binding Characteristics of Mms6, A Bacterial Protein That Promotes the Formation of Superparamagnetic Magnetite Nanoparticles of Uniform Size and Shape

TitleSelf-Assembly and Biphasic Iron-Binding Characteristics of Mms6, A Bacterial Protein That Promotes the Formation of Superparamagnetic Magnetite Nanoparticles of Uniform Size and Shape
Publication TypeJournal Article
Year of Publication2012
AuthorsWang LJ, Prozorov T, Palo PE, Liu XP, Vaknin D, Prozorov R, Mallapragada S, Nilsen-Hamilton M
Journal TitleBiomacromolecules
Volume13
Pages98-105
Date Published01
Type of ArticleArticle
ISBN Number1525-7797
Accession NumberWOS:000298897300011
Keywordsamelogenin nanospheres, beta, biomineralization, crystal, magnetosome formation, MAGNETOTACTIC BACTERIA, MATRIX, membrane, nanocrystals
Abstract

Highly ordered mineralized structures created by living organisms are often hierarchical in structure with fundamental structural elements at nanometer scales. Proteins have been found responsible for forming many of these structures, but the mechanisms by which these biomineralization proteins function are generally poorly understood. To better understand its role in biomineralization, the magnetotactic bacterial protein, Mms6, which promotes the formation in vitro of superparamagnetic magnetite nanoparticles of uniform size and shape, was studied for its structure and function. Mms6 is shown to have two phases of iron binding: one high affinity and stoichiometric and the other low affinity, high capacity, and cooperative with respect to iron. The protein is amphipathic with a hydrophobic N-terminal domain and hydrophilic C-terminal domain. It self-assembles to form a micelle, with most particles consisting of 20-40 monomers, with the hydrophilic C-termini exposed on the outside. Studies of proteins with mutated C-terminal domains show that the C-terminal domain contributes to the stability of this multisubunit particle and binds iron by a mechanism that is sensitive to the arrangement of carboxyl/hydroxyl groups in this domain.

URL<Go to ISI>://WOS:000298897300011
DOI10.1021/bm201278u
Alternate JournalBiomacromolecules