Manganese Homeostasis in Cyanobacteria

Eisenhut, Marion

doi:10.3390/plants9010018

Cited by 16 publications

(12 citation statements)

References 48 publications

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“…Copper, a known toxicant of Prochlorococcus at concentrations as low as 2.3 pM (Mann et al, 2002), and manganese, known to reduce chlorophyll a biosynthesis and photosynthesis in Synechocystis sp. PCC 6803 at 150 µM (Brandenburg et al, 2017;Eisenhut, 2020), also continued to leach from weathered PVC at amounts above those measured in the AMP1 control media and may have also contributed to the toxicity of weathered PVC.…”

Section: Discussionmentioning

confidence: 90%

Assessing the Toxicity of Leachates From Weathered Plastics on Photosynthetic Marine Bacteria Prochlorococcus

et al. 2020

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Marine plastic pollution is a well-recognized, global problem. Research addressing plastic pollution has largely focused on investigating impacts on macroorganisms, with few studies investigating effects on marine microbes. We previously showed that marine Prochlorococcus, which are important contributors to oceanic primary production, suffer declines in growth and photosynthetic activity following exposure to leachates from new plastic bags (HDPE) and plastic matting (PVC). However, as such plastics reside in the environment they will be subject to weathering processes, so it is also important to consider how these may alter the composition and amounts of substances available to leach. Here we report on how plastic leachate toxicity is affected by environmental weathering (17-and 112-days in estuarine water) of these common plastic materials. We found that while toxicity was reduced by weathering, materials weathered for up to 112days continued to leach substances that negatively affected Prochlorococcus growth, photophysiology and membrane integrity. Weathered plastics were found to continue to leach zinc, even after up to 112-days in the environment. The two Prochlorococcus strains tested, NATL2A and MIT9312, showed differences in the sensitivity and timing of their responses, indicating that exposure to leachate from weathered plastics may affect even closely related strains to different degrees. As many marine regions inhabited by Prochlorococcus are likely to be subject to continued accumulation of plastic pollution, our findings highlight the potential for ongoing impacts on these important primary producers.

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Section: Discussionmentioning

confidence: 90%

Assessing the Toxicity of Leachates From Weathered Plastics on Photosynthetic Marine Bacteria Prochlorococcus

et al. 2020

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“…Each cell of S. 6803 an accumulate upto 10 8 Mn 2+ in its envelope layer that acts as a pool for maintaining intracellular Mn ions at 10 6 / cell [45][46]. Under Mn-deficient/ limiting conditions, it is transported through MntABC transporter in the plasma membrane [12,43].…”

Section: Discussionmentioning

confidence: 99%

“…Mn and Fe are both transition metals with atomic numbers of 25 and 26 respectively. Though Fe exists in the environment as Fe 3+ forming insoluble non-bioavailable hydroxides, Mn is predominantly in hydrated Mn 2+ state which is readily taken up by living organisms [43]. Hence, in spite of being in nano molar range, Mn is not considered a limiting factor in aqueous environment [44].…”

Section: Discussionmentioning

confidence: 99%

“…6803 an accumulate upto 10 8 Mn 2+ in its envelope layer that acts as a pool for maintaining intracellular Mn ions at 10 6 / cell [45-46]. Under Mn-deficient/ limiting conditions, it is transported through MntABC transporter in the plasma membrane [12, 43]. Due to similar electronic configuration and high spin (d5) states of Mn 2+ and Fe 3+ , their complexes have similar geometries and hence their promiscuous entry through the same portal (as observed in this study) appears possible and reasonable as the receptor/ transporter might not be able to distinguish between them [38].…”

Section: Discussionmentioning

confidence: 99%

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Iron acquisition across outer membrane: The role of major outer membrane protein Slr1908 under iron supplemented conditions inSynechocystis6803

Agarwal

Choudhury

Akkipeddi

2021

Preprint

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The Ton-B dependent outer membrane (OM) transporters are responsible for active iron (Fe) import in Synechocystis sp. strain PCC 6803 (S. 6803 or WT) under Fe depletion. However, the mechanism of Fe acquisition under Fe supplemented conditions remains uncharacterised. In the present study, functional role of OMP Slr1908 in S. 6803 was addressed by insertional mutagenesis. The Δslr1908 cells exhibited slower growth in the first week in comparison to the WT and displayed an absorption and 77K fluorescence spectrum typical of Fe deficiency. Indeed, the mutant had ∼ 80% less Fe as confirmed by atomic absorption spectroscopy and 55Fe-radiotracer uptake. The iron deficiency was paralleled with low Mn content. The mutant had low SOD content as well as activity, less cytochromes, less chlorophyll content, less Fv/ Fm, lower ETRII and high oxidative stress in comparison to the WT at the end of first week. Interestingly, the mutant showed transcriptional upregulation of iron stress induced protein isiA and isiB signifying intracellular Fe deficiency. Upregulation of OMP Slr0042 was also observed at RNA and protein level. The results indicate that Slr1908 is a major Fe uptake OMP in S. 6803 the deletion of which leads to initial slow growth that gets partially offset by induction of other Fe importing OMPs.

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“…Cyanobacteria, such as Synechocystis, possess additional internal membranes, at which photosynthesis takes place. Here, the manganese exporter (MNX) protein presumably needs to be targeted to both the thylakoid and the plasma membrane in order to perform its physiological function and prevent accumulation of toxic levels of Mn 2+ in the cytosol ( Brandenburg et al, 2017 ; Gandini et al, 2017 ; Eisenhut, 2019 ).…”

Section: Introductionmentioning

confidence: 99%

Gene Replacement in Arabidopsis Reveals Manganese Transport as an Ancient Feature of Human, Plant and Cyanobacterial UPF0016 Proteins

et al. 2021

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The protein family 0016 (UPF0016) is conserved through evolution, and the few members characterized share a function in Mn2+ transport. So far, little is known about the history of these proteins in Eukaryotes. In Arabidopsis thaliana five such proteins, comprising four different subcellular localizations including chloroplasts, have been described, whereas non-photosynthetic Eukaryotes have only one. We used a phylogenetic approach to classify the eukaryotic proteins into two subgroups and performed gene-replacement studies to investigate UPF0016 genes of various origins. Replaceability can be scored readily in the Arabidopsis UPF0016 transporter mutant pam71, which exhibits a functional deficiency in photosystem II. The N-terminal region of the Arabidopsis PAM71 was used to direct selected proteins to chloroplast membranes. Transgenic pam71 lines overexpressing the closest plant homolog (CMT1), human TMEM165 or cyanobacterial MNX successfully restored photosystem II efficiency, manganese binding to photosystem II complexes and consequently plant growth rate and biomass production. Thus AtCMT1, HsTMEM165, and SynMNX can operate in the thylakoid membrane and substitute for PAM71 in a non-native environment, indicating that the manganese transport function of UPF0016 proteins is an ancient feature of the family. We propose that the two chloroplast-localized UPF0016 proteins, CMT1 and PAM71, in plants originated from the cyanobacterial endosymbiont that gave rise to the organelle.

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Manganese Homeostasis in Cyanobacteria

Cited by 16 publications

References 48 publications

Assessing the Toxicity of Leachates From Weathered Plastics on Photosynthetic Marine Bacteria Prochlorococcus

Assessing the Toxicity of Leachates From Weathered Plastics on Photosynthetic Marine Bacteria Prochlorococcus

Iron acquisition across outer membrane: The role of major outer membrane protein Slr1908 under iron supplemented conditions inSynechocystis6803

Gene Replacement in Arabidopsis Reveals Manganese Transport as an Ancient Feature of Human, Plant and Cyanobacterial UPF0016 Proteins

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