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A Comparative Study of Iron Uptake Rates and Mechanisms amongst Marine and Fresh Water Cyanobacteria: Prevalence of Reductive Iron Uptake.

Lis H, Kranzler C, Keren N, Shaked Y - Life (Basel) (2015)

Bottom Line: Uniformity in kin/SA suggests similarity in the mechanism of uptake and indeed, all strains were found to employ a reductive step in the uptake of Fe' and FOB.In contrast, different uptake pathways were found for FeAB along with variations in kin/SA.Cyanobacteria combining both uptake strategies benefit from increased flexibility in accessing different Fe-substrates.

View Article: PubMed Central - PubMed

Affiliation: Interuniversity Institute for Marine Sciences in Eilat, Israel. hagarlis@gmail.com.

ABSTRACT
In this contribution, we address the question of iron bioavailability to cyanobacteria by measuring Fe uptake rates and probing for a reductive uptake pathway in diverse cyanobacterial species. We examined three Fe-substrates: dissolved inorganic iron (Fe') and the Fe-siderophores Ferrioxamine B (FOB) and FeAerobactin (FeAB). In order to compare across substrates and strains, we extracted uptake rate constants (kin = uptake rate/[Fe-substrate]). Fe' was the most bioavailable Fe form to cyanobacteria, with kin values higher than those of other substrates. When accounting for surface area (SA), all strains acquired Fe' at similar rates, as their kin/SA were similar. We also observed homogeneity in the uptake of FOB among strains, but with 10,000 times lower kin/SA values than Fe'. Uniformity in kin/SA suggests similarity in the mechanism of uptake and indeed, all strains were found to employ a reductive step in the uptake of Fe' and FOB. In contrast, different uptake pathways were found for FeAB along with variations in kin/SA. Our data supports the existence of a common reductive Fe uptake pathway amongst cyanobacteria, functioning alone or in addition to siderophore-mediated uptake. Cyanobacteria combining both uptake strategies benefit from increased flexibility in accessing different Fe-substrates.

No MeSH data available.


Related in: MedlinePlus

Short-term 55FeAerobactin uptake in the absence (black triangles) and presence (white triangles) of 200 μM ferrozine (Fz) by iron limited cells of two siderophore (a,b) and two non-siderophore producing (c,d) cyanobacteria. Fe' uptake by cells at 4 °C (cold controls) is also shown. (a) Anabaena UTEX2576 (87nM FeAB) (b) Synechococcus PCC7002 (87 nM FeAB) (c) Synechococcus WH8102 (68nM FeAB) and (d) Synechocystis PCC6803 (150 nM FeAB).
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life-05-00841-f005: Short-term 55FeAerobactin uptake in the absence (black triangles) and presence (white triangles) of 200 μM ferrozine (Fz) by iron limited cells of two siderophore (a,b) and two non-siderophore producing (c,d) cyanobacteria. Fe' uptake by cells at 4 °C (cold controls) is also shown. (a) Anabaena UTEX2576 (87nM FeAB) (b) Synechococcus PCC7002 (87 nM FeAB) (c) Synechococcus WH8102 (68nM FeAB) and (d) Synechocystis PCC6803 (150 nM FeAB).

Mentions: In contrast to FOB and Fe', FeAB exhibits variability in both rate and mechanism of uptake by the different cyanobacterial strains. Linear uptake kinetics of this compound can be observed in the two siderophore producers, Anabaena UTEX 2576 and Synechococcus PCC7002 (Figure 5a,b), as well as in the non siderophore producing, fresh water, Synechocystis PCC6803 (Figure 5d). In the open ocean cyanobacterium, Synechococcus WH8102, the uptake rate is not linear and slows over time (Figure 5c). Similar trends were seen in several other open ocean strains (Figure S6) and we hypothesize that this data reflects adsorption rather than true uptake of FeAB into the cell (see supplemental Section 8).


A Comparative Study of Iron Uptake Rates and Mechanisms amongst Marine and Fresh Water Cyanobacteria: Prevalence of Reductive Iron Uptake.

Lis H, Kranzler C, Keren N, Shaked Y - Life (Basel) (2015)

Short-term 55FeAerobactin uptake in the absence (black triangles) and presence (white triangles) of 200 μM ferrozine (Fz) by iron limited cells of two siderophore (a,b) and two non-siderophore producing (c,d) cyanobacteria. Fe' uptake by cells at 4 °C (cold controls) is also shown. (a) Anabaena UTEX2576 (87nM FeAB) (b) Synechococcus PCC7002 (87 nM FeAB) (c) Synechococcus WH8102 (68nM FeAB) and (d) Synechocystis PCC6803 (150 nM FeAB).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4390881&req=5

life-05-00841-f005: Short-term 55FeAerobactin uptake in the absence (black triangles) and presence (white triangles) of 200 μM ferrozine (Fz) by iron limited cells of two siderophore (a,b) and two non-siderophore producing (c,d) cyanobacteria. Fe' uptake by cells at 4 °C (cold controls) is also shown. (a) Anabaena UTEX2576 (87nM FeAB) (b) Synechococcus PCC7002 (87 nM FeAB) (c) Synechococcus WH8102 (68nM FeAB) and (d) Synechocystis PCC6803 (150 nM FeAB).
Mentions: In contrast to FOB and Fe', FeAB exhibits variability in both rate and mechanism of uptake by the different cyanobacterial strains. Linear uptake kinetics of this compound can be observed in the two siderophore producers, Anabaena UTEX 2576 and Synechococcus PCC7002 (Figure 5a,b), as well as in the non siderophore producing, fresh water, Synechocystis PCC6803 (Figure 5d). In the open ocean cyanobacterium, Synechococcus WH8102, the uptake rate is not linear and slows over time (Figure 5c). Similar trends were seen in several other open ocean strains (Figure S6) and we hypothesize that this data reflects adsorption rather than true uptake of FeAB into the cell (see supplemental Section 8).

Bottom Line: Uniformity in kin/SA suggests similarity in the mechanism of uptake and indeed, all strains were found to employ a reductive step in the uptake of Fe' and FOB.In contrast, different uptake pathways were found for FeAB along with variations in kin/SA.Cyanobacteria combining both uptake strategies benefit from increased flexibility in accessing different Fe-substrates.

View Article: PubMed Central - PubMed

Affiliation: Interuniversity Institute for Marine Sciences in Eilat, Israel. hagarlis@gmail.com.

ABSTRACT
In this contribution, we address the question of iron bioavailability to cyanobacteria by measuring Fe uptake rates and probing for a reductive uptake pathway in diverse cyanobacterial species. We examined three Fe-substrates: dissolved inorganic iron (Fe') and the Fe-siderophores Ferrioxamine B (FOB) and FeAerobactin (FeAB). In order to compare across substrates and strains, we extracted uptake rate constants (kin = uptake rate/[Fe-substrate]). Fe' was the most bioavailable Fe form to cyanobacteria, with kin values higher than those of other substrates. When accounting for surface area (SA), all strains acquired Fe' at similar rates, as their kin/SA were similar. We also observed homogeneity in the uptake of FOB among strains, but with 10,000 times lower kin/SA values than Fe'. Uniformity in kin/SA suggests similarity in the mechanism of uptake and indeed, all strains were found to employ a reductive step in the uptake of Fe' and FOB. In contrast, different uptake pathways were found for FeAB along with variations in kin/SA. Our data supports the existence of a common reductive Fe uptake pathway amongst cyanobacteria, functioning alone or in addition to siderophore-mediated uptake. Cyanobacteria combining both uptake strategies benefit from increased flexibility in accessing different Fe-substrates.

No MeSH data available.


Related in: MedlinePlus