title: Spatial localizations of Mam22 and Mam12 in the magnetosomes of Magnetospirillum magnetotacticum.
abstract: Magnetospirillum magnetotacticum possesses intracellular magnetite particles with a chain-like structure, termed magnetosomes. The bacterium expresses 22-kDa and 12-kDa magnetosome-associated proteins, termed Mam22 (MamA) and Mam12 (MamC), respectively. In this study, we investigated the structure of the purified magnetosomes with transmission electron microscopic techniques and found that the magnetosomes consisted of four compartments, i.e., magnetite crystal, magnetosomal membrane, interparticle connection, and magnetosomal matrix. Furthermore, we determined the precise localizations of Mam22 and Mam12 using immunogold staining of the purified magnetosomes and ultrathin sections of the bacterial cells. Interestingly, most Mam22 existed in the magnetosomal matrix, whereas Mam12 was strictly localized in the magnetosomal membrane. Moreover, the recombinant Mam22 was attached to the magnetosomal matrix of the Mam22-deficient magnetosomes prepared by alkaline treatment, such as 0.1 M Caps-NaOH buffer (pH 11.0). The spatial localization of the magnetosome-associated proteins in the magnetosomal chain provides useful information to elucidate the functional roles of these proteins.
authors.affiliation: Department of Life Science, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan.
authors.forename: Azuma
authors.initials: A
authors.lastname: Taoka
authors.forename: Ryuji
authors.initials: R
authors.lastname: Asada
authors.forename: Hideaki
authors.initials: H
authors.lastname: Sasaki
authors.forename: Kazushi
authors.initials: K
authors.lastname: Anzawa
authors.forename: Long-Fei
authors.initials: LF
authors.lastname: Wu
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Fukumori
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D052203:Ferrosoferric Oxide; D008280:Magnetics; D042201:Magnetospirillum / Q000648:ultrastructure*; D008565:Membrane Proteins / Q000032:analysis / Q000378:metabolism*; D008854:Microscopy, Electron; D016253:Microscopy, Immunoelectron
chemical_list: D001426:Bacterial Proteins; C099987:MAM22 protein, Magnetospirillum magnetotacticum; D008565:Membrane Proteins; D052203:Ferrosoferric Oxide