A Magnetosome-specific GTPase from the Magnetic BacteriumMagnetospirillum magneticum AMB-1

Okamura, Yasuyuki; Takeyama, Haruko; Matsunaga, Tadashi

doi:10.1074/jbc.m106408200

Cited by 64 publications

(79 citation statements)

References 52 publications

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“…This sensing and regulatory module is flanked by the upregulated genes Rru_A3284 and Rru_A3283 encoding for, respectively, a putative molecular chaperone for exported proteins and a GTPase. The latter is similar to the small GTPases involved in the formation of intracellular vesicles in magnetic bacteria (Okamura et al 2001) and could also stabilize the protein transport-related SecA protein (Rru_A0235) (Mü ller et al 1992), which was upregulated 1.8-fold (Po0.05).…”

Section: Message 2 and Related Experimentsmentioning

confidence: 95%

Experimental design and environmental parameters affect Rhodospirillum rubrum S1H response to space flight

et al. 2009

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In view of long-haul space exploration missions, the European Space Agency initiated the MicroEcological Life Support System Alternative (MELiSSA) project targeting the total recycling of organic waste produced by the astronauts into oxygen, water and food using a loop of bacterial and higher plant bioreactors. In that purpose, the a-proteobacterium, Rhodospirillum rubrum S1H, was sent twice to the International Space Station and was analyzed post-flight using a newly developed R. rubrum whole genome oligonucleotide microarray and high throughput gel-free proteomics with Isotope-Coded Protein Label technology. Moreover, in an effort to identify a specific response of R. rubrum S1H to space flight, simulation of microgravity and space-ionizing radiation were performed on Earth under identical culture set-up and growth conditions as encountered during the actual space journeys. Transcriptomic and proteomic data were integrated and permitted to put forward the importance of medium composition and culture set-up on the response of the bacterium to space flight-related environmental conditions. In addition, we showed for the first time that a low dose of ionizing radiation (2 mGy) can induce a significant response at the transcriptomic level, although no change in cell viability and only a few significant differentially expressed proteins were observed. From the MELiSSA perspective, we could argue the effect of microgravity to be minimized, whereas R. rubrum S1H could be more sensitive to ionizing radiation during long-term space exploration mission.

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Section: Message 2 and Related Experimentsmentioning

confidence: 95%

Experimental design and environmental parameters affect Rhodospirillum rubrum S1H response to space flight

et al. 2009

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“…However, MagA maintains a large hydrophobic domain, which renders it unsuitable for assembling membrane proteins. Mms16 was found to be a smaller protein that was abundantly expressed in the BacMP membrane (Okamura et al 2001). It is tightly anchored in the membrane by myristoylation.…”

Section: Protein Assembly On the Surface Of Magnetic Particlesmentioning

confidence: 99%

“…They investigated the precise localization of Mam22 and Mam12 (identical to Mms13 and MamC) and revealed that Mam22 and Mam12 exist in the matrix and the BacMP membrane, respectively. A 16 kDa protein (Mms16), a small GTPase, is speculated to prime the invagination of the cytoplasmic membrane for vesicle formation in M. magneticum AMB-1 (Okamura et al 2001). MpsA shows homology with acetyl-CoA carboxylase (transferase) and the acyl-CoA-binding motif, which is considered to function as a mediator of cytoplasmic membrane invagination (Matsunaga et al 2000b).…”

Section: Protein Analyses Of the Bacmp Membranementioning

confidence: 99%

“…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).…”

Section: Protein Analyses Of the Bacmp Membranementioning

confidence: 99%

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Formation of magnetite by bacteria and its application

Arakaki

Nakazawa

Nemoto

et al. 2008

J. R. Soc. Interface.

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220

176

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Magnetic particles offer high technological potential since they can be conveniently collected with an external magnetic field. Magnetotactic bacteria synthesize bacterial magnetic particles (BacMPs) with well-controlled size and morphology. BacMPs are individually covered with thin organic membrane, which confers high and even dispersion in aqueous solutions compared with artificial magnetites, making them ideal biotechnological materials. Recent molecular studies including genome sequence, mutagenesis, gene expression and proteome analyses indicated a number of genes and proteins which play important roles for BacMP biomineralization. Some of the genes and proteins identified from these studies have allowed us to express functional proteins efficiently onto BacMPs, through genetic engineering, permitting the preservation of the protein activity, leading to a simple preparation of functional protein-magnetic particle complexes. They were applicable to high-sensitivity immunoassay, drug screening and cell separation. Furthermore, fully automated single nucleotide polymorphism discrimination and DNA recovery systems have been developed to use these functionalized BacMPs. The nano-sized fine magnetic particles offer vast potential in new nano-techniques.

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“…Recent molecular studies have postulated the steps of BMP synthesis (7)(8)(9). Several proteins located on or in the BMP membrane have been isolated and analyzed in Magnetospirillum magneticum strain AMB-1.…”

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A Novel Protein Tightly Bound to Bacterial Magnetic Particles in Magnetospirillum magneticum Strain AMB-1

Arakaki

Webb

Matsunaga

2003

Journal of Biological Chemistry

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350

539

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Magnetic bacteria synthesize magnetite crystals with species-dependent morphologies. The molecular mechanisms that control nano-sized magnetite crystal formation and the generation of diverse morphologies are not well understood. From the analysis of magnetite crystalassociated proteins, several low molecular mass proteins tightly bound to bacterial magnetite were obtained from Magnetospirillum magneticum strain AMB-1. These proteins showed common features in their amino acid sequences, which contain hydrophobic Nterminal and hydrophilic C-terminal regions. The Cterminal regions in Mms5, Mms6, Mms7, and Mms13 contain dense carboxyl and hydroxyl groups that bind iron ions. Nano-sized magnetic particles similar to those in magnetic bacteria were prepared by chemical synthesis of magnetite in the presence of the acidic protein Mms6. These proteins may be directly involved in biological magnetite crystal formation in magnetic bacteria.Magnetic bacteria synthesize nano-sized magnetic particles of an iron oxide, magnetite (Fe 3 O 4 ); an iron sulfide, greigite (Fe 3 S 4 ); or a combination of greigite and iron pyrite (Fe 2 S) (1-3). These particles are individually covered with a stable lipid bilayer membrane that mainly consists of lipid and protein (4). The mineral size, type, and morphology of bacterial magnetic particles (BMPs) 1 are highly controlled within bacterial species or strains (5). The species-specific control of BMP formation has focused attention on the possible roles of the surrounding membrane structures.The molecular mechanism of BMP synthesis is a multistep process, including vesicle formation, iron transport, and magnetite crystallization (5, 6). Recent molecular studies have postulated the steps of BMP synthesis (7-9). Several proteins located on or in the BMP membrane have been isolated and analyzed in Magnetospirillum magneticum strain AMB-1. The first event of BMP synthesis is the formation of vesicles. Invagination of the cytoplasmic membrane is primed by a BMP membrane-specific GTPase (Mms16) to form the intracellular vesicle (7). MpsA, a homolog of an acetyltransferase containing a CoA-binding motif, is also considered to be involved in this process (8). The second process in BMP synthesis is iron transport into the BMP vesicles. It appears that ferric iron is reduced on the cell surface, taken into the cytoplasm, transported into the BMP vesicle, and finally oxidized to produce magnetite. The magA gene was isolated through transposon mutagenesis in strain AMB-1 (9). This gene encodes an integral membrane protein that is involved in the transport of iron into the BMP vesicles. The last process is crystallization of magnetite within the vesicle, but the process remains unclear.Other proteins associated with the BMP membrane have been partially characterized in magnetic bacteria to date. To understand the molecular mechanism of magnetite crystallization in M. magneticum AMB-1, several proteins tightly bound to the bacterial magnetite crystals were isolated and characterized. A new class of mi...

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A Magnetosome-specific GTPase from the Magnetic BacteriumMagnetospirillum magneticum AMB-1

Cited by 64 publications

References 52 publications

Experimental design and environmental parameters affect Rhodospirillum rubrum S1H response to space flight

Experimental design and environmental parameters affect Rhodospirillum rubrum S1H response to space flight

Formation of magnetite by bacteria and its application

A Novel Protein Tightly Bound to Bacterial Magnetic Particles in Magnetospirillum magneticum Strain AMB-1

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