Many living organisms transform inorganic atoms into highly ordered crystalline materials. An elegant example of such biomineralization processes is the production of nano-scale magnetic crystals in magnetotactic bacteria. Previous studies implicated the involvement of two putative serine proteases, MamE and MamO, during the early stages of magnetite formation in Magnetospirillum magneticum AMB-1. Here, using genetic analysis and X-ray crystallography, we show that MamO has a degenerate active site, rendering it incapable of protease activity. Instead, MamO promotes magnetosome formation through two genetically distinct, noncatalytic activities: activation of MamE-dependent proteolysis of biomineralization factors and direct binding to transition metal ions. By solving the structure of the protease domain bound to a metal ion, we identify a surface-exposed di-histidine motif in MamO that contributes to metal binding and show that it is required to initiate biomineralization in vivo. Finally, we find that pseudoproteases are widespread in magnetotactic bacteria and that they have evolved independently in three separate taxa. Our results highlight the versatility of protein scaffolds in accommodating new biochemical activities and provide unprecedented insight into the earliest stages of biomineralization.
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http://dx.doi.org/10.1371/journal.pbio.1002402 | DOI Listing |
Front Hum Neurosci
November 2024
The Research Center for Brain Function and Medical Engineering, Asahikawa Medical University, Asahikawa, Japan.
The Earth's abundance of iron has played a crucial role in both generating its geomagnetic field and contributing to the development of early life. In ancient oceans, iron ions, particularly around deep-sea hydrothermal vents, might have catalyzed the formation of macromolecules, leading to the emergence of life and the Last Universal Common Ancestor. Iron continued to influence catalysis, metabolism, and molecular evolution, resulting in the creation of magnetosome gene clusters in magnetotactic bacteria, which enabled these unicellular organisms to detect geomagnetic field.
View Article and Find Full Text PDFBraz J Microbiol
December 2024
Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Av. Carlos Chagas Filho, 373, Cidade Universitária, Rio de Janeiro, RJ, Brazil.
Magnetotactic bacteria align to magnetic field lines while swimming in a behavior known as magnetotaxis. They are diverse phylogenetically and morphologically and include both unicellular and multicellular morphologies. The magnetotactic multicellular prokaryote (MMP) 'Candidatus Magnetoglobus multicellularis' has been extensively studied, even though it remains uncultured up to now.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
December 2024
Commissariat à l'Energie Atomique (CEA), CNRS, Bioscience and Biotechnology Institute of Aix-Marseille (BIAM), Aix-Marseille Université, Saint-Paul-lez-Durance 13115, France.
Magnetotactic bacteria have evolved the remarkable capacity to biomineralize chains of magnetite [Fe(II)Fe(III)O] nanoparticles that align along the geomagnetic field and optimize their navigation in the environment. Mechanisms enabling magnetite formation require the complex action of numerous proteins for iron acquisition, sequestration in dedicated magnetosome organelles, and precipitation into magnetite. The MamP protein contains c-type cytochromes called magnetochrome domains that are found exclusively in magnetotactic bacteria.
View Article and Find Full Text PDFCell Rep
November 2024
Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China; France-China Joint Laboratory for Evolution and Development of Magnetotactic Multicellular Organisms, Chinese Academy of Sciences, Beijing 100029, China; College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China. Electronic address:
ACS Appl Mater Interfaces
December 2024
Departamento de Electricidad y Electrónica, Universidad del País Vasco (UPV/EHU), 48940 Leioa, Spain.
Magnetotactic bacteria have been proposed as ideal biological nanorobots due to the presence of an intracellular chain of magnetic nanoparticles (MNPs), which allows them to be guided and controlled by external magnetic fields and provides them with theragnostic capabilities intrinsic to magnetic nanoparticles, such as magnetic hyperthermia for cancer treatment. Here, we study three different bacterial species, (MSR-1), (AMB-1), and (MV-1), which synthesize magnetite nanoparticles with different morphologies and chain arrangements. We analyzed the impact of these parameters on the effective magnetic anisotropy, , and the heating capacity or Specific Absorption Rate, SAR, under alternating magnetic fields.
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