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Magnetotactic bacteria

About: Magnetotactic bacteria is a research topic. Over the lifetime, 1118 publications have been published within this topic receiving 43741 citations.


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TL;DR: It is demonstrated here that iron containing rolled-up microtubular engines can be magnetized and act as compass needles - they sense the direction of an external magnetic field from afar and align the directionalities of their movements according to the external field.

59 citations

Journal ArticleDOI
TL;DR: The presence of three membrane-associated or periplasmic proteins containing a double cytochrome c signature motif CXXCH: MamE, MamP and MamT suggests the existence of an electron-transport chain inside the magnetosome, contributing to the process of biocrystallization.
Abstract: Magnetotactic bacteria consist of a group of taxonomically, physiologically and morphologically diverse prokaryotes, with the singular ability to align with geomagnetic field lines, a phenomenon referred to as magnetotaxis. This magnetotactic property is due to the presence of iron-rich crystals embedded in lipidic vesicles forming an organelle called the magnetosome. Magnetosomes are composed of single-magnetic-domain nanocrystals of magnetite (Fe 3 O 4 ) or greigite (Fe 3 S 4 ) embedded in biological membranes, thereby forming a prokaryotic organelle. Four specific steps are described in this organelle formation: (i) membrane specialization, (ii) iron acquisition, (iii) magnetite (or greigite) biocrystallization, and (iv) magnetosome alignment. The formation of these magnetic crystals is a genetically controlled process, which is governed by enzyme-catalysed processes. On the basis of protein sequence analysis of genes known to be involved in magnetosome formation in Magnetospirillum magneticum AMB-1, we have identified a subset of three membrane-associated or periplasmic proteins containing a double cytochrome c signature motif CXXCH: MamE, MamP and MamT. The presence of these proteins suggests the existence of an electron-transport chain inside the magnetosome, contributing to the process of biocrystallization. We have performed heterologous expression in E. coli of the cytochrome c motif-containing domains of MamE, MamP and MamT. Initial biophysical characterization has confirmed that MamE, MamP and MamT are indeed c -type cytochromes. Furthermore, determination of redox potentials for this new family of c -type cytochromes reveals midpoint potentials of −76 and −32 mV for MamP and MamE respectively.

59 citations

Journal ArticleDOI
TL;DR: The co‐ordinated functions of Mms proteins regulate the morphology of the cubo‐octahedral magnetite crystals in magnetotactic bacteria.
Abstract: Magnetotactic bacteria synthesize magnetosomes comprised of membrane-enveloped single crystalline magnetite (Fe3 O4 ). The size and morphology of the nano-sized magnetite crystals (< 100 nm) are highly regulated and bacterial species dependent. However, the control mechanisms of magnetite crystal morphology remain largely unknown. The group of proteins, called Mms (Mms5, Mms6, Mms7, and Mms13), was previously isolated from the surface of cubo-octahedral magnetite crystals in Magnetospirillum magneticum strain AMB-1. Analysis of an mms6 gene deletion mutant suggested that the Mms6 protein plays a major role in the regulation of magnetite crystal size and morphology. In this study, we constructed various mms gene deletion mutants and characterized the magnetite crystals formed by the mutant strains. Comparative analysis showed that all mms genes were involved in the promotion of crystal growth in different manners. The phenotypic characterization of magnetites also suggested that these proteins are involved in controlling the geometries of the crystal surface structures. Thus, the co-ordinated functions of Mms proteins regulate the morphology of the cubo-octahedral magnetite crystals in magnetotactic bacteria.

58 citations

Journal ArticleDOI
TL;DR: Magnetotactic bacteria orient and migrate along magnetic field lines using a submicron assembly of single-magnetic domain iron mineral particles that elegantly solves the problem of how to construct a magnetic dipole that is large enough to be oriented in the geomagnetic field at ambient temperature, yet fit inside a micron-sized cell.

58 citations

Journal ArticleDOI
TL;DR: Findings suggest that magnetosomes are covered with MamA oligomers in near-native environments and provide important clues to the supramolecular architecture of the bacterial organelle, the magnetosome, and insight into the function of the proteins localized in the organelle.
Abstract: The unique ability of magnetotactic bacteria to navigate along a geomagnetic field is accomplished with the help of prokaryotic organelles, magnetosomes. The magnetosomes have well-ordered chain-like structures, comprising membrane-enveloped, nano-sized magnetic crystals, and various types of specifically associated proteins. In this study, we applied atomic force microscopy (AFM) to investigate the spatial configuration of isolated magnetosomes from Magnetospirillum magneticum AMB-1 in near-native buffer conditions. AFM observation revealed organic material with a ∼7-nm thickness surrounding a magnetite crystal. Small globular proteins, identified as magnetosome-associated protein MamA, were distributed on the mica surface around the magnetosome. Immuno-labeling with AFM showed that MamA is located on the magnetosome surface. In vitro experiments showed that MamA proteins interact with each other and form a high molecular mass complex. These findings suggest that magnetosomes are covered with MamA oligomers in near-native environments. Furthermore, nanodissection revealed that magnetosomes are built with heterogeneous structures that comprise the organic layer. This study provides important clues to the supramolecular architecture of the bacterial organelle, the magnetosome, and insight into the function of the proteins localized in the organelle.

57 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202339
202288
202137
202061
201950
201873