Please use this identifier to cite or link to this item: http://hdl.handle.net/1893/20029
Appears in Collections:Biological and Environmental Sciences Journal Articles
Peer Review Status: Refereed
Title: Lack of Control of Nitrite Assimilation by Ammonium in an Oceanic Picocyanobacterium, Synechococcus sp. Strain WH 8103
Authors: Wyman, Michael
Bird, Clare
Contact Email: michael.wyman@stir.ac.uk
Keywords: ABILITY
ABUNDANCE
AMMONIUM
ASSIMILATION
CELLS
Control
expression
gene
Genes
Growth
LEVEL
levels
marine
media
NITROGEN
other
RAE
STRAINS
SURFACE
TRAIT
WATER
WATERS
Issue Date: May-2007
Publisher: American Society for Microbiology
Citation: Wyman M & Bird C (2007) Lack of Control of Nitrite Assimilation by Ammonium in an Oceanic Picocyanobacterium, Synechococcus sp. Strain WH 8103, Applied and Environmental Microbiology, 73 (9), pp. 3028-3033.
Abstract: In cyanobacteria, the transcriptional activator NtcA is involved in global nitrogen control and, in the absence of ammonium, regulates the expression of genes involved in the assimilation of alternative nitrogen sources. The oceanic picocyanobacterium Synechococcus sp. strain WH 8103 harbors a copy of ntcA, but in the present study, we show that unlike other marine cyanobacteria that have been investigated, this strain is capable of coassimilating nitrite when grown in the presence of ammonium. Transcript levels for the genes encoding the nitrate/nitrite-bispecific permease NrtP and nitrate reductase (NarB) were substantially down-regulated by ammonium, whereas the abundances of nitrite reductase (NirA) transcripts were similar in nitrite- and ammonium-grown cells. The growth of Synechococcus sp. strain WH 8103 in medium containing both ammonium and nitrite resulted in only minor changes in the expression profile in comparison to that of nitrite-grown cells with the exception that the gene encoding the high-affinity ammonium transporter Amt1 was down-regulated to the levels seen in ammonium-grown cells. Whereas the expression of nrtP, narB, and amt1 appears to be NtcA dependent in this marine cyanobacterium, the transcription and expression of nirA appear not to be. The ability to coassimilate nitrite and reduced-nitrogen sources like ammonium may be an adaptive trait that enables oceanic strains like Synechococcus sp. strain WH 8103 to exploit the low nitrite concentrations found in oceanic surface waters that are not available to their principal and more numerous competitor, Prochlorococcus.
Type: Journal Article
URI: http://hdl.handle.net/1893/20029
DOI Link: http://dx.doi.org/10.1128/AEM.02606-06
Rights: The publisher does not allow this work to be made publicly available in this Repository. Please use the Request a Copy feature at the foot of the Repository record to request a copy directly from the author. You can only request a copy if you wish to use this work for your own research or private study.
Affiliation: Biological and Environmental Sciences
Biological and Environmental Sciences

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