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MamA as a Model Protein for Structure-Based Insight into the Evolutionary Origins of Magnetotactic Bacteria.

Zeytuni N, Cronin S, Lefèvre CT, Arnoux P, Baran D, Shtein Z, Davidov G, Zarivach R - PLoS ONE (2015)

Bottom Line: As such, this allows us to perform structural- and phylogenetic-based analyses using a variety of previously determined MamA from a diverse range of MTB species across various phylogenetic groups.We found that MamA has remained remarkably constant throughout evolution with minimal change between different taxa despite sequence variations.These findings, coupled with the generation of phylogenetic trees using both amino acid sequences and 16S rRNA, indicate that magnetotaxis likely did not spread via horizontal gene transfer and instead has a significantly earlier, primordial origin.

View Article: PubMed Central - PubMed

Affiliation: Department of Life Sciences and The National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Beer Sheva, Israel.

ABSTRACT
MamA is a highly conserved protein found in magnetotactic bacteria (MTB), a diverse group of prokaryotes capable of navigating according to magnetic fields - an ability known as magnetotaxis. Questions surround the acquisition of this magnetic navigation ability; namely, whether it arose through horizontal or vertical gene transfer. Though its exact function is unknown, MamA surrounds the magnetosome, the magnetic organelle embedding a biomineralised nanoparticle and responsible for magnetotaxis. Several structures for MamA from a variety of species have been determined and show a high degree of structural similarity. By determining the structure of MamA from Desulfovibrio magneticus RS-1 using X-ray crystallography, we have opened up the structure-sequence landscape. As such, this allows us to perform structural- and phylogenetic-based analyses using a variety of previously determined MamA from a diverse range of MTB species across various phylogenetic groups. We found that MamA has remained remarkably constant throughout evolution with minimal change between different taxa despite sequence variations. These findings, coupled with the generation of phylogenetic trees using both amino acid sequences and 16S rRNA, indicate that magnetotaxis likely did not spread via horizontal gene transfer and instead has a significantly earlier, primordial origin.

No MeSH data available.


Circular dichroism measurements of ArsTM (purple) and MamAΔ41 proteins from RS-1 (Blue) Mbav (orange), AMB-1 (green) and MSR-1 (red).(A) Circular dichroism spectra. (B) Circular dichroism melting curve measurements at 222 nm. Wild type MamAΔ41RS-1 presents the lowest thermostability, with a melting temperature of ~40°C, while the triple mutated MamAΔ41RS-1 (ArsTM) exhibits a slightly increased thermostability with a melting temperature of ~ 51°C. MamAΔ41AMB-1, MamAΔ41MSR-1 and MamAΔ41Mbav present melting temperatures of ~51, 53 and 65°C, respectively.
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pone.0130394.g006: Circular dichroism measurements of ArsTM (purple) and MamAΔ41 proteins from RS-1 (Blue) Mbav (orange), AMB-1 (green) and MSR-1 (red).(A) Circular dichroism spectra. (B) Circular dichroism melting curve measurements at 222 nm. Wild type MamAΔ41RS-1 presents the lowest thermostability, with a melting temperature of ~40°C, while the triple mutated MamAΔ41RS-1 (ArsTM) exhibits a slightly increased thermostability with a melting temperature of ~ 51°C. MamAΔ41AMB-1, MamAΔ41MSR-1 and MamAΔ41Mbav present melting temperatures of ~51, 53 and 65°C, respectively.

Mentions: The described variations between stabilisation patterns of the NTD among MamA proteins from different species can be linked to the overall thermostability seen in circular dichroism spectrometry. Melting temperature measurements revealed that MamAΔ41RS-1 presents a reduced thermostability, with a melting temperature of 45°C, while MamAΔ41AMB-1, MamAΔ41MSR-1 and MamAΔ41Mbav present melting temperatures of 51, 53 and 65°C, respectively (Fig 6). The most thermostable protein is MamAΔ41Mbav, which employs only polar interactions to stabilise its NTD, whereas the least thermostable protein is MamAΔ41RS-1, which employs only hydrophobic interactions. In between this thermostability range we can find MamAΔ41 from Magnetospirillum species, which employ both types of interactions. We could also see that subjecting MamAΔ41RS-1 to the triple surface entropy reduction mutations increased its thermostability by 6°C, by which it reached the same temperature as MamAΔ41AMB-1. In order to obtain coherent and comparable results, we examined the octameric forms for both MamAΔ41RS-1 and ArsTM during the circular dichroism spectrometry measurements. Accordingly, we believe that such slightly increased thermostability is due to the increased structural stability between ArsTM monomers when assembled as oligomers in solution (S1 Fig).


MamA as a Model Protein for Structure-Based Insight into the Evolutionary Origins of Magnetotactic Bacteria.

Zeytuni N, Cronin S, Lefèvre CT, Arnoux P, Baran D, Shtein Z, Davidov G, Zarivach R - PLoS ONE (2015)

Circular dichroism measurements of ArsTM (purple) and MamAΔ41 proteins from RS-1 (Blue) Mbav (orange), AMB-1 (green) and MSR-1 (red).(A) Circular dichroism spectra. (B) Circular dichroism melting curve measurements at 222 nm. Wild type MamAΔ41RS-1 presents the lowest thermostability, with a melting temperature of ~40°C, while the triple mutated MamAΔ41RS-1 (ArsTM) exhibits a slightly increased thermostability with a melting temperature of ~ 51°C. MamAΔ41AMB-1, MamAΔ41MSR-1 and MamAΔ41Mbav present melting temperatures of ~51, 53 and 65°C, respectively.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4482739&req=5

pone.0130394.g006: Circular dichroism measurements of ArsTM (purple) and MamAΔ41 proteins from RS-1 (Blue) Mbav (orange), AMB-1 (green) and MSR-1 (red).(A) Circular dichroism spectra. (B) Circular dichroism melting curve measurements at 222 nm. Wild type MamAΔ41RS-1 presents the lowest thermostability, with a melting temperature of ~40°C, while the triple mutated MamAΔ41RS-1 (ArsTM) exhibits a slightly increased thermostability with a melting temperature of ~ 51°C. MamAΔ41AMB-1, MamAΔ41MSR-1 and MamAΔ41Mbav present melting temperatures of ~51, 53 and 65°C, respectively.
Mentions: The described variations between stabilisation patterns of the NTD among MamA proteins from different species can be linked to the overall thermostability seen in circular dichroism spectrometry. Melting temperature measurements revealed that MamAΔ41RS-1 presents a reduced thermostability, with a melting temperature of 45°C, while MamAΔ41AMB-1, MamAΔ41MSR-1 and MamAΔ41Mbav present melting temperatures of 51, 53 and 65°C, respectively (Fig 6). The most thermostable protein is MamAΔ41Mbav, which employs only polar interactions to stabilise its NTD, whereas the least thermostable protein is MamAΔ41RS-1, which employs only hydrophobic interactions. In between this thermostability range we can find MamAΔ41 from Magnetospirillum species, which employ both types of interactions. We could also see that subjecting MamAΔ41RS-1 to the triple surface entropy reduction mutations increased its thermostability by 6°C, by which it reached the same temperature as MamAΔ41AMB-1. In order to obtain coherent and comparable results, we examined the octameric forms for both MamAΔ41RS-1 and ArsTM during the circular dichroism spectrometry measurements. Accordingly, we believe that such slightly increased thermostability is due to the increased structural stability between ArsTM monomers when assembled as oligomers in solution (S1 Fig).

Bottom Line: As such, this allows us to perform structural- and phylogenetic-based analyses using a variety of previously determined MamA from a diverse range of MTB species across various phylogenetic groups.We found that MamA has remained remarkably constant throughout evolution with minimal change between different taxa despite sequence variations.These findings, coupled with the generation of phylogenetic trees using both amino acid sequences and 16S rRNA, indicate that magnetotaxis likely did not spread via horizontal gene transfer and instead has a significantly earlier, primordial origin.

View Article: PubMed Central - PubMed

Affiliation: Department of Life Sciences and The National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Beer Sheva, Israel.

ABSTRACT
MamA is a highly conserved protein found in magnetotactic bacteria (MTB), a diverse group of prokaryotes capable of navigating according to magnetic fields - an ability known as magnetotaxis. Questions surround the acquisition of this magnetic navigation ability; namely, whether it arose through horizontal or vertical gene transfer. Though its exact function is unknown, MamA surrounds the magnetosome, the magnetic organelle embedding a biomineralised nanoparticle and responsible for magnetotaxis. Several structures for MamA from a variety of species have been determined and show a high degree of structural similarity. By determining the structure of MamA from Desulfovibrio magneticus RS-1 using X-ray crystallography, we have opened up the structure-sequence landscape. As such, this allows us to perform structural- and phylogenetic-based analyses using a variety of previously determined MamA from a diverse range of MTB species across various phylogenetic groups. We found that MamA has remained remarkably constant throughout evolution with minimal change between different taxa despite sequence variations. These findings, coupled with the generation of phylogenetic trees using both amino acid sequences and 16S rRNA, indicate that magnetotaxis likely did not spread via horizontal gene transfer and instead has a significantly earlier, primordial origin.

No MeSH data available.