Comparison of the kinetics of iron release from a marine (Trichodesmium erythraeum) Dps protein and mammalian ferritin in the presence and absence of ligands

Castruita, Madeli; Elmegreen, Lauren A.; Shaked, Yeala; Stiefel, Edward I.; Morel, François M. M.

doi:10.1016/j.jinorgbio.2007.07.022

Cited by 18 publications

(25 citation statements)

References 40 publications

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“…The observed lag time in our system (with no changes in cell abundance; Figure 3a) between bloom initiation (T 0 ) and the induction of PCD (T 2d ) may have resulted from the consistent slow release of intracellular Fe (Castruita et al, 2007) prior to the PCD-induced collapse. Following bloom collapse (T 3d ), MC gene expression and caspase activity rates were significantly reduced from their maximal levels (T 2d ) by 76-100% and 40-80%, respectively (Figure 3b).…”

Section: Abrupt and Synchronized Bloom Demisementioning

confidence: 80%

“…In the aquatic environment, natural populations of Trichodesmium encounter similar Fe limitation where they can mobilize and reincorporate Fe from intracellular storages, such as 'DNA-binding proteins from starved cells', to meet cellular demands for growth (Castruita et al, 2007). The observed lag time in our system (with no changes in cell abundance; Figure 3a) between bloom initiation (T 0 ) and the induction of PCD (T 2d ) may have resulted from the consistent slow release of intracellular Fe (Castruita et al, 2007) prior to the PCD-induced collapse.…”

Section: Abrupt and Synchronized Bloom Demisementioning

confidence: 99%

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Programmed cell death in the marine cyanobacterium Trichodesmium mediates carbon and nitrogen export

et al. 2013

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The extent of carbon (C) and nitrogen (N) export to the deep ocean depends upon the efficacy of the biological pump that transports primary production to depth, thereby preventing its recycling in the upper photic zone. The dinitrogen-fixing (diazotrophic) Trichodesmium spp. contributes significantly to oceanic C and N cycling by forming extensive blooms in nutrient-poor tropical and subtropical regions. These massive blooms generally collapse several days after forming, but the cellular mechanism responsible, along with the magnitude of associated C and N export processes, are as yet unknown. Here, we used a custom-made, 2-m high water column to simulate a natural bloom and to specifically test and quantify whether the programmed cell death (PCD) of Trichodesmium mechanistically regulates increased vertical flux of C and N. Our findings demonstrate that extremely rapid development and abrupt, PCD-induced demise (within 2-3 days) of Trichodesmium blooms lead to greatly elevated excretions of transparent exopolymers and a massive downward pulse of particulate organic matter. Our results mechanistically link autocatalytic PCD and bloom collapse to quantitative C and N export fluxes, suggesting that PCD may have an impact on the biological pump efficiency in the oceans.

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Section: Abrupt and Synchronized Bloom Demisementioning

confidence: 80%

Section: Abrupt and Synchronized Bloom Demisementioning

confidence: 99%

Programmed cell death in the marine cyanobacterium Trichodesmium mediates carbon and nitrogen export

et al. 2013

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“…As a result, the transition of cyanobacterial cultures into an iron-limited state is slow. An alternative to the wash procedure is the use of iron chelators (Castruita et al, 2007;Shcolnick et al, 2007). The effect of metal chelators is 2-fold: they prevent the formation of insoluble iron oxide crystals, and they compete with the cyanobacterial cells for iron binding.…”

Section: Resultsmentioning

confidence: 99%

The Mechanism of Iron Homeostasis in the Unicellular Cyanobacterium Synechocystis sp. PCC 6803 and Its Relationship to Oxidative Stress

et al. 2009

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In this article, we demonstrate the connection between intracellular iron storage and oxidative stress response in cyanobacteria. Iron is essential for the survival of all organisms. However, the redox properties that make iron a valuable cofactor also lead to oxidative interactions, resulting in the formation of harmful radicals. Therefore, iron accumulation in cells should be tightly regulated, a process in which ferritin family proteins play an important role. Synechocystis sp. PCC 6803 contains two ferritintype storage complexes, bacterioferritin and MrgA. Previous studies demonstrated the role of bacterioferritin and MrgA in iron storage. In addition, MrgA was found to play a key role in oxidative stress response. Here, we examined the dual role of the ferritin family proteins using physiological and transcriptomic approaches. Microarray analysis of iron-limited wild-type and DmrgA cultures revealed a substantial up-regulation of oxidative stress-related genes in mutant cells. The PerR regulator was found to play an important role in that process. Furthermore, we were able to demonstrate the connection between internal iron quota, the presence of the two storage complexes, and the sensitivity to externally applied oxidative stress. These data suggest a pivotal role for the ferritin-type proteins of Synechocystis sp. PCC 6803 in coordinating iron homeostasis and in oxidative stress response. The combined action of the two complexes allows for the safe accumulation and release of iron from storage by minimizing damage resulting from interactions between reduced iron and the oxygen radicals that are produced in abundance by the photosynthetic apparatus.

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“…The Fe core of bacterioferritins tends to be disordered and normally contains more phosphate (P i : Fe 1 : 1 to 1 : 2) (Andrews 1998;Treffry et al 1987). The core composition of Dps proteins is less known, but phosphate incorporation into the iron core of Trichodesmium erythraeum Dps protein has been reported (P i : Fe 1 : 4) (Castruita et al 2006).…”

mentioning

confidence: 99%

“…Although ferritins are ubiquitous to all forms of life, the study of these proteins in marine phytoplankton is limited. Genomic analysis of oceanic phytoplankton reveals the presence of iron-storage genes in several cyanobacteria and a Dps protein from T. erythraeum (Dps tery ) has been overexpressed and partially characterized (Castruita et al 2006). But the role of iron-storage proteins in the marine environment remains elusive.…”

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confidence: 99%

Availability of iron from iron‐storage proteins to marine phytoplankton

Castruita

Shaked

Elmegreen

et al. 2008

Limnology & Oceanography

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We examined the bioavailability of iron-storage proteins-including representatives of maxi-and miniferritins-to various species of marine phytoplankton. Both eukaryotic and prokaryotic species were able to grow rapidly with horse spleen ferritin (HoSF) or deoxyribonucleic acid (DNA)-binding proteins from starved cells (Dps) from Trichodesmium erythraeum as the sole Fe source in the medium. In the presence of ethylenediaminetetra-acetic acid (EDTA), cells grown with HoSF or Dps maintained exponential growth rates similar to those obtained at the same concentration of FeEDTA. Growth was also observed in the absence of EDTA, showing that a complexing agent is not necessary for Fe availability. The bioavailability of Fe in these storage proteins apparently results from a spontaneous release of Fe(III) to solution with an effective first-order rate constant ,0.15 d 21 . Genes coding for iron-storage proteins are common in DNA samples from seawater. In iron-deprived marine ecosystems, iron-storage proteins may be important constituents of the recycled iron pool and modulate its availability to phytoplankton.

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Comparison of the kinetics of iron release from a marine (Trichodesmium erythraeum) Dps protein and mammalian ferritin in the presence and absence of ligands

Cited by 18 publications

References 40 publications

Programmed cell death in the marine cyanobacterium Trichodesmium mediates carbon and nitrogen export

Programmed cell death in the marine cyanobacterium Trichodesmium mediates carbon and nitrogen export

The Mechanism of Iron Homeostasis in the Unicellular Cyanobacterium Synechocystis sp. PCC 6803 and Its Relationship to Oxidative Stress

Availability of iron from iron‐storage proteins to marine phytoplankton

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