Common ancestry of iron oxide- and iron-sulfide-based biomineralization in magnetotactic bacteria

Abstract

Magnetosomes are prokaryotic organelles produced by magnetotactic bacteria that consist of nanometer-sized magnetite (Fe 3 O 4 ) or/and greigite (Fe 3 S 4 ) magnetic crystals enveloped by a lipid bilayer membrane. In magnetite-producing magnetotactic bacteria, proteins present in the magnetosome membrane modulate biomineralization of the magnetite crystal. In these microorganisms, genes that encode for magnetosome membrane proteins as well as genes involved in the construction of the magnetite magnetosome chain, the mam and mms genes, are organized within a genomic island. However, partially because there are presently no greigite-producing magnetotactic bacteria in pure culture, little is known regarding the greigite biomineralization process in these organisms including whether similar genes are involved in the process. Here using cultureindependent techniques, we now show that mam genes involved in the production of magnetite magnetosomes are also present in greigite-producing magnetotactic bacteria. This finding suggest that the biomineralization of magnetite and greigite did not have evolve independently (that is, magnetotaxis is polyphyletic) as once suggested. Instead, results presented here are consistent with a model in which the ability to biomineralize magnetosomes and the possession of the mam genes was acquired by bacteria from a common ancestor, that is, the magnetotactic trait is monophyletic.

Deciphering unusual uncultured magnetotactic multicellular prokaryotes through genomics

“…Magnetic enrichment of cells, genomic amplification and sequencing were performed according to Abreu et al (2011). Sampling occurred during 2007 until 2009; the double magnetic enrichment was performed directly after sampling and the purified Ca.…”

“…M. multicellularis and phylogenetic analysis indicated that the biomineralization of magnetite and greigite evolved from a common ancestor Lefèvre et al, 2013a). Here, we compared magnetotactic bacterial genomes based on the coverage and similarity value percentages used to analyze biomineralization genes on a previous study (1e À 05 E-value, 22% coverage and 50% similarity; Abreu et al, 2011). Ca.…”

Physiological origin of biogenic magnetic nanoparticles in health and disease: from bacteria to humans

“…Single-crystal magnetite or greigite is incorporated in the magnetosome membrane, which besides phospholipids contains a number of magnetosome-associated proteins ( Figure 1A). 12,24,25 Magnetosomes in MTB are arranged in chains, [4][5][6] bearing dozens of separate magnetite NPs of size 10-135 nm 26,27 (see Figure 1B and C). These BMNP chains follow the long axis of the bacterium, and are attached to its membrane.…”

“…10 The genetic control of BMNP biomineralization has only been studied in detail in MTB, with the corresponding biomineralization proteins identified. [11][12][13][14][15] However, the physiological origin of BMNPs in other organisms, including humans, has attracted much attention for more than 30 years. The problem is very important, since elevated BMNP levels are associated with a number of human diseases, including neurodegenerative disorders and cancer.…”

Microbes: Mini Iron Factories

“…One of the most intriguing and fascinating examples of importance of microbes in geology is the role they play in ore deposition and mineralization which is referred to as biomineralization. Recently, there has been increasing interest in processes leading to the biomineralization of Iron oxides [16,17] because it is believed that microbes had a significant role in the deposition of BIFs.…”