Eitan Salomon | Washington University in St. Louis (original) (raw)

Papers by Eitan Salomon

Research paper thumbnail of Mn Transport and the Assembly of Photosystem II

Bioenergetic Processes of Cyanobacteria, 2011

Research paper thumbnail of Acclimation to environmentally relevant Mn concentrations rescues a cyanobacterium from the detrimental effects of iron limitation

Environmental microbiology, Jan 2, 2015

The functions of micronutrient transition metals in photosynthetic organisms are interconnected. ... more The functions of micronutrient transition metals in photosynthetic organisms are interconnected. So are the effects of their limitation. Here we present evidence for the effects of Mn limitation on Fe limitation responses in the cyanobacterium Synechocystis sp. PCC 6803. Low Mn acclimated cells were able to detect and respond to iron insufficiency by inducing specific Fe transporters. However, they did not bleach, lose additional photosystem I activity and did not induce isiA transcription. Induction of the isiAB operon is a hallmark of iron limitation, and the isiA protein is considered to be central to the acclimation of the photosynthetic apparatus. Our results suggest that acclimation to environmentally relevant Mn concentrations that much lower than those used in laboratory experiments reduces the detrimental effects of iron limitation and modifies iron stress responses.

Research paper thumbnail of Manganese in Biological Systems: Transport and Function

PATAI'S Chemistry of Functional Groups, 2009

ABSTRACT

Research paper thumbnail of The response of Hordeum spontaneum desert ecotype to drought and excessive light intensity is characterized by induction of O2 dependent photochemical activity and anthocyanin accumulation

Plant Science, 2013

The goal of the current research was to study the role of anthocyanin accumulation, O 2 -related ... more The goal of the current research was to study the role of anthocyanin accumulation, O 2 -related photochemical processes and non-photochemical quenching (NPQ) in the response of desert and Mediterranean plants to drought and excessive light.

Research paper thumbnail of Manganese Limitation Induces Changes in the Activity and in the Organization of Photosynthetic Complexes in the Cyanobacterium Synechocystis sp. Strain PCC 6803

PLANT PHYSIOLOGY, 2011

Manganese (Mn) ions are essential for oxygen evolution activity in photoautotrophs. In this paper... more Manganese (Mn) ions are essential for oxygen evolution activity in photoautotrophs. In this paper, we demonstrate the dynamic response of the photosynthetic apparatus to changes in Mn bioavailability in cyanobacteria. Cultures of the cyanobacterium Synechocystis PCC 6803 could grow on Mn concentrations as low as 100 nM without any observable effect on their physiology. Below this threshold, a decline in the photochemical activity of photosystem II (PSII) occurred, as evident by lower oxygen evolution rates, lower maximal photosynthetic yield of PSII values, and faster Q A reoxidation rates. In 77 K chlorophyll fluorescence spectroscopy, a peak at 682 nm was observed. After ruling out the contribution of phycobilisome and iron stress-induced IsiA proteins, this band was attributed to the accumulation of partially assembled PSII. Surprisingly, the increase in the 682-nm peak was paralleled by a decrease in the 720-nm peak, dominated by PSI fluorescence. The effect on PSI was confirmed by measurements of the P 700 photochemical activity. The loss of activity was the result of two processes: loss of PSI core proteins and changes in the organization of PSI complexes. Blue native-polyacrylamide gel electrophoresis analysis revealed a Mn limitation-dependent dissociation of PSI trimers into monomers. The sensitive range for changes in the organization of the photosynthetic apparatus overlaps with the range of Mn concentrations measured in natural environments. We suggest that the ability to manipulate PSI content and organization allows cyanobacteria to balance electron transport rates between the photosystems. At naturally occurring Mn concentrations, such a mechanism will provide important protection against light-induced damage.

Research paper thumbnail of Balancing photosynthetic electron flow is critical for cyanobacterial acclimation to nitrogen limitation

Biochimica et Biophysica Acta (BBA) - Bioenergetics, 2013

Other uses, including reproduction and distribution, or selling or licensing copies, or posting t... more Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited.

Research paper thumbnail of The hierarchy of transition metal homeostasis: iron controls manganese accumulation in a unicellular cyanobacterium

Biochimica et biophysica acta, 2014

Iron and manganese are part of a small group of transition metals required for photosynthetic ele... more Iron and manganese are part of a small group of transition metals required for photosynthetic electron transport. Here, we present evidence for a functional link between iron and manganese homeostasis. In the unicellular cyanobacterium, Synechocystis sp. PCC 6803, Fe and Mn deprivation resulted in distinct modifications of the physiological status. The effect on growth and photosynthetic activity under Fe limitation were more severe than those observed under Mn limitation. Moreover, the intracellular elemental quotas of Fe and Mn were found to be linked. Fe limitation reduced the intracellular Mn quota. Mn limitation did not exert a reciprocal effect on Fe quotas. Microarray analysis comparing Mn and Fe limitation revealed a stark difference in the extent of the transcriptional response to the two limiting conditions, reflective of the physiological responses. The effects of Fe limitation on the transcriptional network are widespread while the effects on Mn limitation are highly spe...

Research paper thumbnail of Mn Transport and the Assembly of Photosystem II

Bioenergetic Processes of Cyanobacteria, 2011

Research paper thumbnail of Acclimation to environmentally relevant Mn concentrations rescues a cyanobacterium from the detrimental effects of iron limitation

Environmental microbiology, Jan 2, 2015

The functions of micronutrient transition metals in photosynthetic organisms are interconnected. ... more The functions of micronutrient transition metals in photosynthetic organisms are interconnected. So are the effects of their limitation. Here we present evidence for the effects of Mn limitation on Fe limitation responses in the cyanobacterium Synechocystis sp. PCC 6803. Low Mn acclimated cells were able to detect and respond to iron insufficiency by inducing specific Fe transporters. However, they did not bleach, lose additional photosystem I activity and did not induce isiA transcription. Induction of the isiAB operon is a hallmark of iron limitation, and the isiA protein is considered to be central to the acclimation of the photosynthetic apparatus. Our results suggest that acclimation to environmentally relevant Mn concentrations that much lower than those used in laboratory experiments reduces the detrimental effects of iron limitation and modifies iron stress responses.

Research paper thumbnail of Manganese in Biological Systems: Transport and Function

PATAI'S Chemistry of Functional Groups, 2009

ABSTRACT

Research paper thumbnail of The response of Hordeum spontaneum desert ecotype to drought and excessive light intensity is characterized by induction of O2 dependent photochemical activity and anthocyanin accumulation

Plant Science, 2013

The goal of the current research was to study the role of anthocyanin accumulation, O 2 -related ... more The goal of the current research was to study the role of anthocyanin accumulation, O 2 -related photochemical processes and non-photochemical quenching (NPQ) in the response of desert and Mediterranean plants to drought and excessive light.

Research paper thumbnail of Manganese Limitation Induces Changes in the Activity and in the Organization of Photosynthetic Complexes in the Cyanobacterium Synechocystis sp. Strain PCC 6803

PLANT PHYSIOLOGY, 2011

Manganese (Mn) ions are essential for oxygen evolution activity in photoautotrophs. In this paper... more Manganese (Mn) ions are essential for oxygen evolution activity in photoautotrophs. In this paper, we demonstrate the dynamic response of the photosynthetic apparatus to changes in Mn bioavailability in cyanobacteria. Cultures of the cyanobacterium Synechocystis PCC 6803 could grow on Mn concentrations as low as 100 nM without any observable effect on their physiology. Below this threshold, a decline in the photochemical activity of photosystem II (PSII) occurred, as evident by lower oxygen evolution rates, lower maximal photosynthetic yield of PSII values, and faster Q A reoxidation rates. In 77 K chlorophyll fluorescence spectroscopy, a peak at 682 nm was observed. After ruling out the contribution of phycobilisome and iron stress-induced IsiA proteins, this band was attributed to the accumulation of partially assembled PSII. Surprisingly, the increase in the 682-nm peak was paralleled by a decrease in the 720-nm peak, dominated by PSI fluorescence. The effect on PSI was confirmed by measurements of the P 700 photochemical activity. The loss of activity was the result of two processes: loss of PSI core proteins and changes in the organization of PSI complexes. Blue native-polyacrylamide gel electrophoresis analysis revealed a Mn limitation-dependent dissociation of PSI trimers into monomers. The sensitive range for changes in the organization of the photosynthetic apparatus overlaps with the range of Mn concentrations measured in natural environments. We suggest that the ability to manipulate PSI content and organization allows cyanobacteria to balance electron transport rates between the photosystems. At naturally occurring Mn concentrations, such a mechanism will provide important protection against light-induced damage.

Research paper thumbnail of Balancing photosynthetic electron flow is critical for cyanobacterial acclimation to nitrogen limitation

Biochimica et Biophysica Acta (BBA) - Bioenergetics, 2013

Other uses, including reproduction and distribution, or selling or licensing copies, or posting t... more Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited.

Research paper thumbnail of The hierarchy of transition metal homeostasis: iron controls manganese accumulation in a unicellular cyanobacterium

Biochimica et biophysica acta, 2014

Iron and manganese are part of a small group of transition metals required for photosynthetic ele... more Iron and manganese are part of a small group of transition metals required for photosynthetic electron transport. Here, we present evidence for a functional link between iron and manganese homeostasis. In the unicellular cyanobacterium, Synechocystis sp. PCC 6803, Fe and Mn deprivation resulted in distinct modifications of the physiological status. The effect on growth and photosynthetic activity under Fe limitation were more severe than those observed under Mn limitation. Moreover, the intracellular elemental quotas of Fe and Mn were found to be linked. Fe limitation reduced the intracellular Mn quota. Mn limitation did not exert a reciprocal effect on Fe quotas. Microarray analysis comparing Mn and Fe limitation revealed a stark difference in the extent of the transcriptional response to the two limiting conditions, reflective of the physiological responses. The effects of Fe limitation on the transcriptional network are widespread while the effects on Mn limitation are highly spe...