Photoferrotrophy: Remains of an Ancient Photosynthesis in Modern Environments

Camacho, Antonio; Walter, Xavier Alexis; Picazo, Antonio; Zopfi, Jakob

doi:10.3389/fmicb.2017.00323

Cited by 73 publications

(60 citation statements)

References 218 publications

(286 reference statements)

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“…(e.g., Ehrenreich and Widdel, 1994;Kappler and Newman, 2004;Camacho et al, 2017) or by oxidizing sulfide…”

Section: Origin Of Anoxygenic Photosynthesismentioning

confidence: 99%

Geological and Geochemical Constraints on the Origin and Evolution of Life

Sleep

2018

Astrobiology

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The traditional tree of life from molecular biology with last universal common ancestor (LUCA) branching into bacteria and archaea (though fuzzy) is likely formally valid enough to be a basis for discussion of geological processes on the early Earth. Biologists infer likely properties of nodal organisms within the tree and, hence, the environment they inhabited. Geologists both vet tenuous trees and putative origin of life scenarios for geological and ecological reasonability and conversely infer geological information from trees. The latter approach is valuable as geologists have only weakly constrained the time when the Earth became habitable and the later time when life actually existed to the long interval between ∼4.5 and ∼3.85 Ga where no intact surface rocks are known. With regard to vetting, origin and early evolution hypotheses from molecular biology have recently centered on serpentinite settings in marine and alternatively land settings that are exposed to ultraviolet sunlight. The existence of these niches on the Hadean Earth is virtually certain. With regard to inferring geological environment from genomics, nodes on the tree of life can arise from true bottlenecks implied by the marine serpentinite origin scenario and by asteroid impact. Innovation of a very useful trait through a threshold allows the successful organism to quickly become very abundant and later root a large clade. The origin of life itself, that is, the initial Darwinian ancestor, the bacterial and archaeal roots as free-living cellular organisms that independently escaped hydrothermal chimneys above marine serpentinite or alternatively from shallow pore-water environments on land, the Selabacteria root with anoxygenic photosynthesis, and the Terrabacteria root colonizing land are attractive examples that predate the geological record. Conversely, geological reasoning presents likely events for appraisal by biologists. Asteroid impacts may have produced bottlenecks by decimating life. Thermophile roots of bacteria and archaea as well as a thermophile LUCA are attractive.

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“…(e.g., Ehrenreich and Widdel, 1994;Kappler and Newman, 2004;Camacho et al, 2017) or by oxidizing sulfide…”

Section: Origin Of Anoxygenic Photosynthesismentioning

confidence: 99%

Geological and Geochemical Constraints on the Origin and Evolution of Life

Sleep

2018

Astrobiology

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“…Iron is one of the most ancient and abundant transition metal ions in living organisms, 1,2 as it was highly available as ferrous ion in the early days of terrestrial life. 3 Iron is essential to all forms of life and participates in fundamental biological processes, such as photosynthesis, respiration and nitrogen fixation. 4,5 In cells, it is normally found in the +2 (ferrous) and/or +3 (ferric) oxidation states.…”

Section: Introductionmentioning

confidence: 99%

The human iron-proteome†

et al. 2018

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Organisms from all kingdoms of life use iron-proteins in a multitude of functional processes. We applied a bioinformatics approach to investigate the human portfolio of iron-proteins. We separated ironproteins based on the chemical nature of their metal-containing cofactors: individual iron ions, heme cofactors and iron-sulfur clusters. We found that about 2% of human genes encode an iron-protein.Of these, 35% are proteins binding individual iron ions, 48% are heme-binding proteins and 17% are iron-sulfur proteins. More than half of the human iron-proteins have a catalytic function. Indeed, we predict that 6.5% of all human enzymes are iron-dependent. This percentage is quite different for the various enzyme classes. Human oxidoreductases feature the largest fraction of iron-dependent family members (about 37%). The distribution of iron proteins in the various cellular compartments is uneven.In particular, the mitochondrion and the endoplasmic reticulum are enriched in iron-proteins with respect to the average content of the cell. Finally, we observed that genes encoding iron-proteins are more frequently associated to pathologies than the all other human genes on average. The present research provides an extensive overview of iron usage by the human proteome, and highlights several specific features of the physiological role of iron ions in human cells. Significance to metallomicsIron is one of the most ancient and abundant metal ions in living organisms: it participates in fundamental biological processes, such as photosynthesis, and respiration. It is an essential metal ion for humans. Here, we applied a bioinformatics approach to predict the entire set of human proteins that use iron as cofactor. We found that about 2% of human genes encode an iron-protein. In particular, 35% are proteins binding individual iron ions, 48% are heme-binding proteins and 17% are iron-sulfur proteins. Most of these proteins are enzymes: 37% of the human oxidoreductases need an iron ion to perform their catalytic mechanisms. The analysis of the subcellular location highlighted that some organelles are enriched in iron-proteins, in particular about 7% of the proteins localized in the endoplasmic reticulum and in the mitochondrion bind iron. Finally, our data show that mutations in genes encoding iron-binding proteins are more likely to be associated with pathology than all human genes on average.

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“…The microbiological processes and biogeochemical cycling occurring in ferruginous meromictic lakes are often invoked as having analogy to redox‐stratified, ferruginous oceans of the Archean and Proterozoic eons (Poulton & Canfield, ). For instance, processes of microbial Fe(II) oxidation and Fe(III) reduction have been observed to impact the carbon cycle across the O 2 and Fe(II) redoxcline in lakes (e.g., Berg et al, ; Berg et al, ; Camacho, Walter, et al, ; Gorlenko, Vainstein, & Chebotarev, ; Savvichev et al, ; Walter et al, ). These processes are also envisioned to have impacted the carbon cycle in ferruginous oceans (Posth, Konhauser, & Kappler, ).…”

Section: Discussionmentioning

confidence: 99%

Biogeochemical and physical controls on methane fluxes from two ferruginous meromictic lakes

et al. 2019

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Meromictic lakes with anoxic bottom waters often have active methane cycles whereby methane is generally produced biogenically under anoxic conditions and oxidized in oxic surface waters prior to reaching the atmosphere. Lakes that contain dissolved ferrous iron in their deep waters (i.e., ferruginous) are rare, but valuable, as geochemical analogues of the conditions that dominated the Earth's oceans during the Precambrian when interactions between the iron and methane cycles could have shaped the greenhouse regulation of the planet's climate. Here, we explored controls on the methane fluxes from Brownie Lake and Canyon Lake, two ferruginous meromictic lakes that contain similar concentrations (max. >1 mM) of dissolved methane in their bottom waters. The order Methanobacteriales was the dominant methanogen detected in both lakes. At Brownie Lake, methanogen abundance, an increase in methane concentration with respect to depths closer to the sediment, and isotopic data suggest methanogenesis is an active process in the anoxic water column. At Canyon Lake, methanogenesis occurred primarily in the sediment. The most abundant aerobic methane‐oxidizing bacteria present in both water columns were associated with the Gammaproteobacteria, with little evidence of anaerobic methane oxidizing organisms being present or active. Direct measurements at the surface revealed a methane flux from Brownie Lake that was two orders of magnitude greater than the flux from Canyon Lake. Comparison of measured versus calculated turbulent diffusive fluxes indicates that most of the methane flux at Brownie Lake was non‐diffusive. Although the turbulent diffusive methane flux at Canyon Lake was attenuated by methane oxidizing bacteria, dissolved methane was detected in the epilimnion, suggestive of lateral transport of methane from littoral sediments. These results highlight the importance of direct measurements in estimating the total methane flux from water columns, and that non‐diffusive transport of methane may be important to consider from other ferruginous systems.

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Photoferrotrophy: Remains of an Ancient Photosynthesis in Modern Environments

Cited by 73 publications

References 218 publications

Geological and Geochemical Constraints on the Origin and Evolution of Life

Geological and Geochemical Constraints on the Origin and Evolution of Life

The human iron-proteome†

Biogeochemical and physical controls on methane fluxes from two ferruginous meromictic lakes

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