Insight into the assembly properties and functional organisation of the magnetotactic bacterial Actin-like Homolog, MamK
Magnetotactic bacteria (MTB) synthesize magnetosomes, which are intracellular vesicles comprising a magnetic particle. A series of magnetosomes arrange themselves in chains to form a magnetic dipole that enables the cell to orient itself along the Earth’s magnetic field. MamK, an actin-like homolog...
| Main Authors: | , , , , , , |
|---|---|
| Other Authors: | |
| Format: | Journal Article |
| Language: | English |
| Published: |
2013
|
| Subjects: | |
| Online Access: | https://hdl.handle.net/10356/95350 http://hdl.handle.net/10220/9192 |
| _version_ | 1826122563108995072 |
|---|---|
| author | Fuentes, Gloria. Narang, Ram. Khare, Varsha. Verma, Chandra Shekhar. Sonkaria, Sanjiv. Fischer, Anna. Faivre, Damien. |
| author2 | School of Biological Sciences |
| author_facet | School of Biological Sciences Fuentes, Gloria. Narang, Ram. Khare, Varsha. Verma, Chandra Shekhar. Sonkaria, Sanjiv. Fischer, Anna. Faivre, Damien. |
| author_sort | Fuentes, Gloria. |
| collection | NTU |
| description | Magnetotactic bacteria (MTB) synthesize magnetosomes, which are intracellular vesicles comprising a magnetic particle. A series of magnetosomes arrange themselves in chains to form a magnetic dipole that enables the cell to orient itself along the Earth’s magnetic field. MamK, an actin-like homolog of MreB has been identified as a central component in this organisation. Gene deletion, fluorescence microscopy and in vitro studies have yielded mechanistic differences in the filament assembly of MamK with other bacterial cytoskeletal proteins within the cell. With little or no information on the structural and behavioural characteristics of MamK outside the cell, the mamK gene from Magnetospirillium gryphiswaldense was cloned and expressed to better understand the differences in the cytoskeletal properties with its bacterial homologues MreB and acitin. Despite the low sequence identity shared between MamK and MreB (22%) and actin (18%), the behaviour of MamK monitored by light scattering broadly mirrored that of its bacterial cousin MreB primarily in terms of its pH, salt, divalent metal-ion and temperature dependency. The broad size variability of MamK filaments revealed by light scattering studies was supported by transmission electron microscopy (TEM) imaging. Filament morphology however, indicated that MamK conformed to linearly orientated filaments that appeared to be distinctly dissimilar compared to MreB suggesting functional differences between these homologues. The presence of a nucleotide binding domain common to actin-like proteins was demonstrated by its ability to function both as an ATPase and GTPase. Circular dichroism and structural homology modelling showed that MamK adopts a protein fold that is consistent with the ‘classical’ actin family architecture but with notable structural differences within the smaller domains, the active site region and the overall surface electrostatic potential. |
| first_indexed | 2024-10-01T05:50:31Z |
| format | Journal Article |
| id | ntu-10356/95350 |
| institution | Nanyang Technological University |
| language | English |
| last_indexed | 2024-10-01T05:50:31Z |
| publishDate | 2013 |
| record_format | dspace |
| spelling | ntu-10356/953502023-02-28T17:01:45Z Insight into the assembly properties and functional organisation of the magnetotactic bacterial Actin-like Homolog, MamK Fuentes, Gloria. Narang, Ram. Khare, Varsha. Verma, Chandra Shekhar. Sonkaria, Sanjiv. Fischer, Anna. Faivre, Damien. School of Biological Sciences DRNTU::Science::Biological sciences Magnetotactic bacteria (MTB) synthesize magnetosomes, which are intracellular vesicles comprising a magnetic particle. A series of magnetosomes arrange themselves in chains to form a magnetic dipole that enables the cell to orient itself along the Earth’s magnetic field. MamK, an actin-like homolog of MreB has been identified as a central component in this organisation. Gene deletion, fluorescence microscopy and in vitro studies have yielded mechanistic differences in the filament assembly of MamK with other bacterial cytoskeletal proteins within the cell. With little or no information on the structural and behavioural characteristics of MamK outside the cell, the mamK gene from Magnetospirillium gryphiswaldense was cloned and expressed to better understand the differences in the cytoskeletal properties with its bacterial homologues MreB and acitin. Despite the low sequence identity shared between MamK and MreB (22%) and actin (18%), the behaviour of MamK monitored by light scattering broadly mirrored that of its bacterial cousin MreB primarily in terms of its pH, salt, divalent metal-ion and temperature dependency. The broad size variability of MamK filaments revealed by light scattering studies was supported by transmission electron microscopy (TEM) imaging. Filament morphology however, indicated that MamK conformed to linearly orientated filaments that appeared to be distinctly dissimilar compared to MreB suggesting functional differences between these homologues. The presence of a nucleotide binding domain common to actin-like proteins was demonstrated by its ability to function both as an ATPase and GTPase. Circular dichroism and structural homology modelling showed that MamK adopts a protein fold that is consistent with the ‘classical’ actin family architecture but with notable structural differences within the smaller domains, the active site region and the overall surface electrostatic potential. Published version 2013-02-20T05:58:38Z 2019-12-06T19:13:11Z 2013-02-20T05:58:38Z 2019-12-06T19:13:11Z 2012 2012 Journal Article Sonkaria, S., Fuentes, G., Verma, C. S., Narang, R., Khare, V., Fischer, A., et al. (2012). Insight into the Assembly Properties and Functional Organisation of the Magnetotactic Bacterial Actin-like Homolog, MamK. PLoS ONE, 7(5). 1932-6203 https://hdl.handle.net/10356/95350 http://hdl.handle.net/10220/9192 10.1371/journal.pone.0034189 22586444 en PLoS ONE © 2012 The Authors. application/pdf |
| spellingShingle | DRNTU::Science::Biological sciences Fuentes, Gloria. Narang, Ram. Khare, Varsha. Verma, Chandra Shekhar. Sonkaria, Sanjiv. Fischer, Anna. Faivre, Damien. Insight into the assembly properties and functional organisation of the magnetotactic bacterial Actin-like Homolog, MamK |
| title | Insight into the assembly properties and functional organisation of the magnetotactic bacterial Actin-like Homolog, MamK |
| title_full | Insight into the assembly properties and functional organisation of the magnetotactic bacterial Actin-like Homolog, MamK |
| title_fullStr | Insight into the assembly properties and functional organisation of the magnetotactic bacterial Actin-like Homolog, MamK |
| title_full_unstemmed | Insight into the assembly properties and functional organisation of the magnetotactic bacterial Actin-like Homolog, MamK |
| title_short | Insight into the assembly properties and functional organisation of the magnetotactic bacterial Actin-like Homolog, MamK |
| title_sort | insight into the assembly properties and functional organisation of the magnetotactic bacterial actin like homolog mamk |
| topic | DRNTU::Science::Biological sciences |
| url | https://hdl.handle.net/10356/95350 http://hdl.handle.net/10220/9192 |
| work_keys_str_mv | AT fuentesgloria insightintotheassemblypropertiesandfunctionalorganisationofthemagnetotacticbacterialactinlikehomologmamk AT narangram insightintotheassemblypropertiesandfunctionalorganisationofthemagnetotacticbacterialactinlikehomologmamk AT kharevarsha insightintotheassemblypropertiesandfunctionalorganisationofthemagnetotacticbacterialactinlikehomologmamk AT vermachandrashekhar insightintotheassemblypropertiesandfunctionalorganisationofthemagnetotacticbacterialactinlikehomologmamk AT sonkariasanjiv insightintotheassemblypropertiesandfunctionalorganisationofthemagnetotacticbacterialactinlikehomologmamk AT fischeranna insightintotheassemblypropertiesandfunctionalorganisationofthemagnetotacticbacterialactinlikehomologmamk AT faivredamien insightintotheassemblypropertiesandfunctionalorganisationofthemagnetotacticbacterialactinlikehomologmamk |