Spatial localizations of Mam22 and Mam12 in the magnetosomes of Magnetospirillum magnetotacticum.
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.
Taoka
Azuma
A
Department of Life Science, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan.
Asada
Ryuji
R
Sasaki
Hideaki
H
Anzawa
Kazushi
K
Wu
Long-Fei
LF
Fukumori
Yoshihiro
Y
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
D001426:Bacterial Proteins; C099987:MAM22 protein, Magnetospirillum magnetotacticum; D008565:Membrane Proteins; D052203:Ferrosoferric Oxide