Origin of magnetosome membrane: Proteomic analysis of magnetosome membrane and comparison with cytoplasmic membrane

Abstract

Prokaryotes are known to have evolved one or more unique organelles. Although several hypotheses have been proposed concerning the biogenesis of these intracellular components, the majority of these proposals remains unclear. Magnetotactic bacteria synthesize intracellular magnetosomes that are enclosed by lipid bilayer membranes. From the identification and characterization of several surface and transmembrane magnetosome proteins, we have postulated that magnetosomes are derived from the cytoplasmic membrane (CM). To confirm this hypothesis, a comparative proteomic analysis of the magnetosome membrane (MM) and CM of the magnetotactic bacterium, Magnetospirillum magneticum AMB-1, was undertaken. Based on the whole genome sequence of M. magneticum AMB-1, 78 identified MM proteins were also found to be prevalent in the CM, several of which are related to magnetosome biosynthesis, such as Mms13, which is tightly bound on the magnetite surface. Fatty acid analysis was also conducted, and showed a striking similarity between the CM and MM profiles. These results suggest that the MM is derived from the CM.

Formation of magnetite by bacteria and its application

“…In the analysis of BacMP membrane proteins from M. gryphiswaldense MSR-1, approximately 30 proteins were identified; a considerable number of these proteins were found to be assigned in gene clusters located within the magnetosome island (Grünberg et al 2004). A similar examination was attempted with M. magneticum AMB-1, wherein a total of 78 proteins were identified from the surface of its BacMP (figure 3; Tanaka et al 2006). In order to investigate the origin of the BacMP membrane, proteins acquired from AMB-1 cells were separated into the outer membrane, cytoplasmic membrane, BacMP membrane and cytoplasmic-periplasmic fractions.…”

“…To elucidate the molecular mechanism of BacMP biomineralization, proteome analyses of BacMP membrane proteins have currently been conducted in M. magneticum AMB-1 (Matsunaga et al 2000b;Okamura et al 2000Okamura et al , 2001Arakaki et al 2003;Tanaka et al 2006), M. gryphiswaldense MSR-1 (Grünberg et al 2001(Grünberg et al , 2004 and M. magnetotacticum MS-1 (Okuda et al 1996), from which numerous novel proteins with potentially crucial roles in BacMP biomineralization have been discovered. In the analysis of BacMP membrane proteins from M. gryphiswaldense MSR-1, approximately 30 proteins were identified; a considerable number of these proteins were found to be assigned in gene clusters located within the magnetosome island (Grünberg et al 2004).…”

Single-Molecule Imaging on Living Bacterial Cell Surface by High-Speed AFM

“…The result corresponded to the previous proteomic analysis of M. magneticum AMB-1 membrane fractions. 28 The most abundant protein in the outer membrane fraction is a 40-kDa protein (Fig. 4g) that was identified as a porin homolog (amb0025: Msp1).…”

A Ferromagnetic Resonance Study of Iron Complexes as Biologically Synthesized in Magnetic Bacteria

“…[8][9][10][11][12][13] Based upon these studies, several models for magnetosome formation have been proposed. 1,14) While many studies focused on the characterization of the proteins, little research on the process of formation of magnetites crystals has been carried out.…”