Global transcriptome analysis of salt acclimated Prochlorococcus AS9601

Abstract

Molecular processes leading to salt stress acclimation in the model cyanobacterium Prochlorococcus are not known. To address this, we used RNA sequencing (RNAseq) to compare the global transcriptome of two exponential-phase populations of Prochlorococcus AS9601 cells - acclimated to high salt (5%, w/v) and normal seawater salt (3.8%, w/v). Experiments showed that salt acclimated cells exhibit slower growth rates with a doubling time almost twice as controls. Approximately 1/3 of the genome was found to be differentially expressed (p-value <0.05), but a considerably large number of these genes are "hypothetical proteins" with unknown function. Transcript abundance were higher for genes involved in respiratory electron flow, carbon fixation, osmolyte/compatible solute biosynthesis and inorganic ion transport. Many of the highly expressed genes are 'high light inducible proteins' believed to be part of the general Prochlorococcus stress response. Transcript abundance were lower for genes involved in photosynthetic electron transport and cell division. The relative reduction in transcript abundance for genes encoding proteins containing heme groups and iron transporters suggests cellular iron requirements in salt acclimated cells maybe lower. The results presented here provide the first glimpse into global gene expression changes in Prochlorococcus cells due to salt stress.

Comparative Genomics of the Baltic Sea Toxic Cyanobacteria Nodularia spumigena UHCC 0039 and Its Response to Varying Salinity

“…Chaperones, molecules with an important role in protein folding, protection, and repair under stress conditions, were highly up-regulated in our study. Their role in maintaining protein integrity under low and high salt stress was previously described (Fulda et al, 2006 ; Al-Hosani et al, 2015 ). The cell wall is the first part encountering a new environment, and thus cell wall structure and functioning have a crucial role in adaptation.…”

“…Genomes of cyanobacteria are highly dynamic and the induction of either general or stress-specific genes and regulatory systems enable them to proliferate in a changing environment. Transcriptome modifications that acclimate to elevated salt concentration are induced rapidly (Billis et al, 2014 ), but complete acclimation of metabolic processes resulting in the inhibition of cell division requires a longer time period (Qiao et al, 2013 ; Al-Hosani et al, 2015 ). For example, work on Synechocystis sp.…”

“…In general, salt shock inhibits the proper functioning of several proteins and metabolic processes, such as photosynthesis, central metabolism, and cellular growth, and the high demand for the reconstruction of cellular metabolism is obvious (Marin et al, 2004 ; Allakhverdiev and Murata, 2008 ; Billis et al, 2014 ; Rai et al, 2014 ; Al-Hosani et al, 2015 ). Chaperones, molecules with an important role in protein folding, protection, and repair under stress conditions, were highly up-regulated in our study.…”

Insight into the genome and brackish water adaptation strategies of toxic and bloom-forming Baltic Sea Dolichospermum sp. UHCC 0315

“…The induction of either general or stress-specific genes and regulatory systems enables cyanobacteria to thrive, even in changing environments. The transcriptional regulatory system of model cyanobacteria for adapting to elevated salt concentrations is induced rapidly 31 , but complete acclimation of metabolic processes resulting in inhibition of cell division requires longer periods of time 33,34 . For example, a study of Synechocystis sp.…”

Improved Salt Tolerance and Metabolomics Analysis of Synechococcus elongatus UTEX 2973 by Overexpressing Mrp Antiporters

“…The pentose phosphate pathway belongs to the carbon fixation pathway in S. elongatus. It was reported that the transcript abundance of carbon fixation was increased in Prochlorococcus AS9601 under salt stress (Al-Hosani et al, 2015). The results suggested that Syn2973 elevated pentose phosphate pathway, which might fix more carbon dioxide for salt tolerance, and overexpressing 7002-Mrp has no inference on the mechanism.…”