Sudden motility reversal indicates sensing of magnetic field gradients in <i>Magnetospirillum magneticum</i> AMB-1 strain

González, Lina María; Ruder, Warren C.; Mitchell, Aaron P.; Messner, William C.; LeDuc, Philip R.

doi:10.1038/ismej.2014.224

Cited by 20 publications

(21 citation statements)

References 55 publications

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“…Our results indicate a threshold drag of 9.5 pN, corresponding to a flow velocity of 550 µm s −1 , where magnetotaxis enables MTB to overcome counterdirectional flow. These findings are relevant to marine ecosystems, where both the direction of the geomagnetic field and the flow influence the orientation and, therefore, the migration of MTB.…”

Section: Discussionmentioning

confidence: 79%

“…Several biological and physical factors may influence the response of MTB to the magnetic field and shear flow, including the hydrodynamic effects due to orientation of the cell body with respect to flow, the interaction of the dipole moment and the magnetic field, and the molecular composition of the cell such as intercellular protein content . With respect to biological factors, the interaction of methyl‐accepting chemotaxis protein (MCP) and the filamentous cytoskeletal protein MamK is suggested to play an important role in magnetotactic behavior of M. magneticum AMB‐1, particularly at low magnetic field strength (≈1 mT) .…”

Section: Discussionmentioning

confidence: 99%

“…Specifically, the magnetic torque on the magnetosome is transduced via MamK to MCP Amb0994 . The cell senses the magnetic torque by Amb0994 and actively controls the flagellar motor to reorient along the magnetic field lines . MTB lacking Amb0994, or with an overproduction of Amb0994, fail to respond to an applied magnetic field .…”

Section: Discussionmentioning

confidence: 99%

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Magnetotaxis Enables Magnetotactic Bacteria to Navigate in Flow

Yazdi

Nosrati

Stevens

et al. 2017

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Magnetotactic bacteria (MTB) play an important role in Earth's biogeochemical cycles by transporting minerals in aquatic ecosystems, and have shown promise for controlled transport of microscale objects in flow conditions. However, how MTB traverse complex flow environments is not clear. Here, using microfluidics and high-speed imaging, it is revealed that magnetotaxis enables directed motion of Magnetospirillum magneticum over long distances in flow velocities ranging from 2 to 1260 µm s , corresponding to shear rates ranging from 0.2 to 142 s -a range relevant to both aquatic environments and biomedical applications. The ability of MTB to overcome a current is influenced by the flow, the magnetic field, and their relative orientation. MTB can overcome 2.3-fold higher flow velocities when directed to swim perpendicular to the flow as compared to upstream, as the latter orientation induces higher drag. The results indicate a threshold drag of 9.5 pN, corresponding to a flow velocity of 550 µm s , where magnetotaxis enables MTB to overcome counterdirectional flow. These findings bring new insights into the interactions of MTB with complex flow environments relevant to aquatic ecosystems, while suggesting opportunities for in vivo applications of MTB in microbiorobotics and targeted drug delivery.

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Section: Discussionmentioning

confidence: 79%

Section: Discussionmentioning

confidence: 99%

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Magnetotaxis Enables Magnetotactic Bacteria to Navigate in Flow

Yazdi

Nosrati

Stevens

et al. 2017

Small

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“…This phenomenon further explains why the cells possessing amb0994 can be active in sensing the external fields to coordinate their motions, rather than being completely passive to orientation. Another study revealed that M. magneticum AMB-1 cells could sense magnetic field gradients and respond to them by reversing direction (González et al, 2015 ). The author speculates that this difference in the field could be torqueing the cells and relaying this signal to Amb0994.…”

Section: Discussionmentioning

confidence: 99%

Efficient Genome Editing of Magnetospirillum magneticum AMB-1 by CRISPR-Cas9 System for Analyzing Magnetotactic Behavior

et al. 2018

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Magnetotactic bacteria (MTB) are a diverse group of microorganisms capable of using geomagnetic fields for navigation. This magnetotactic behavior can help microorganisms move toward favorable habitats for optimal growth and reproduction. A comprehensive understanding of the magnetotactic mechanism at molecular levels requires highly efficient genomic editing tools, which remain underdeveloped in MTB. Here, we adapted an engineered CRISPR-Cas9 system for efficient inactivation of genes in a widely used MTB model strain, Magnetospirillum magneticum AMB-1. By combining a nuclease-deficient Cas9 (dCas9) and single-guide RNA (sgRNA), a CRISPR interference system was successfully developed to repress amb0994 expression. Furthermore, we constructed an in-frame deletion mutant of amb0994 by developing a CRISPR-Cas9 system. This mutant produces normal magnetosomes; however, its response to abrupt magnetic field reversals is faster than wild-type strain. This behavioral difference is probably a consequence of altered flagella function, as suggested with our dynamics simulation study by modeling M. magneticum AMB-1 cell as an ellipsoid. These data indicate that, Amb0994 is involved in the cellular response to magnetic torque changes via controlling flagella. In summary, this study, besides contributing to a better understanding of magnetotaxis mechanism, demonstrated the CRISPR-(d)Cas9 system as a useful genetic tool for efficient genome editing in MTB.

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“…This phenomenon further explains why the cells possessing amb0994 can be active in sensing the external fields to coordinate their motions, rather than being completely passive to orientation. Another study revealed that M. magneticum AMB-1 cells can sense magnetic field gradients and respond to them by reversing direction [59]. The author speculates that this difference in the field could be torqueing the cells and relaying this signal to Amb0994.…”

Section: Discussionmentioning

confidence: 99%

Efficient genome editing ofMagnetospirillum magneticumAMB-1 by CRISPR-Cas9 system for analyzing magnetotactic behavior

Chen

Zhang

Chen

et al. 2018

Preprint

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Magnetotactic bacteria are a diverse group of microorganisms with the ability to use geomagnetic fields for direction sensing. This magnetotactic behavior can help microorganisms move towards favorable habitats for optimal growth and reproduction. Highly efficient genomic editing is very useful for a comprehensive understanding of the magnetotactic mechanism at the molecular level. In this study, we adapted an engineered CRISPR-cas9 system for efficient inactivation of gene in a widely used magnetotactic bacteria model strain, Magnetospirillum magneticum AMB-1. By combining an engineered nuclease-deficient Cas9 and single-guide RNA, a CRISPR interference system was successfully developed to silence amb0994 expression. More importantly, we succeeded in the construction of a single amb0994 gene deletion mutant using CRISPR-Cas9 with approximate 60-fold high efficiency compared to classical homology double-crossing replacement procedure. This mutant synthesized normally the magnetosomes, but reacted quicker and with less time than the wild-type strain to abrupt magnetic field reversals. A dynamics simulation by modeling M. magneticum AMB-1 cell as an ellipsoid showed that the difference of the motions between wild and Δamb0994 is due to flagellar influence. The behavior observation being consistent with dynamics simulation indicated that Amb0994 is involved in the cellular response to magnetic torque change via controlling flagella. Besides the contribution to a better understanding of the magnetotaxis mechanism, this study demonstrates the CRISPR system as a useful genetic toolbox for high-efficiency genome editing in magnetotactic bacteria.

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Sudden motility reversal indicates sensing of magnetic field gradients in Magnetospirillum magneticum AMB-1 strain

Cited by 20 publications

References 55 publications

Magnetotaxis Enables Magnetotactic Bacteria to Navigate in Flow

Magnetotaxis Enables Magnetotactic Bacteria to Navigate in Flow

Efficient Genome Editing of Magnetospirillum magneticum AMB-1 by CRISPR-Cas9 System for Analyzing Magnetotactic Behavior

Efficient genome editing ofMagnetospirillum magneticumAMB-1 by CRISPR-Cas9 system for analyzing magnetotactic behavior

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