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Open Access Research

The quantitative proteomic response of Synechocystis sp. PCC6803 to phosphate acclimation

Matthew A Fuszard1, Saw Yen Ow2, Chee Sian Gan3, Josseilin Noirel2, Nigel G Ternan4, Geoff McMullan4, Catherine A Biggs2, Kenneth F Reardon5 and Phillip C Wright2*

Author Affiliations

1 BSRC Mass Spectrometry and Proteomics Facility, Department of Chemistry, University of St Andrews, St Andrews, KY16 9ST, UK

2 ChELSI Institute, Department of Chemical and Biological Engineering, University of Sheffield, Sheffield, S1 3JD, UK

3 Agilent Technologies, Singapore, Singapore

4 School of Biomedical Sciences, University of Ulster, Coleraine, County Londonderry, BT52 1SA, UK

5 Department of Chemical and Biological Engineering, Colorado State University, Fort Collins, CO, 80523-1370, USA

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Aquatic Biosystems 2013, 9:5  doi:10.1186/2046-9063-9-5

Published: 26 February 2013

Abstract

Background

Inorganic phosphate (Pi) is a critical nutrient for all life and is periodically limiting in marine and freshwater provinces, yet little is understood how organisms acclimate to fluctuations in Pi within their environment. To investigate whole cell adaptation, we grew Synechocystis sp. PCC6803, a model freshwater cyanobacterium, in 3%, and 0.3% inorganic phosphate (Pi) media. The cells were allowed to acclimate over 60 days, and cells were harvested for quantitative high throughput mass spectrometry-based proteomics using the iTRAQ™ labelling technology.

Results

In total, 120 proteins were identified, and 52 proteins were considered differentially abundant compared to the control. Alkaline phosphatase (APase) activities correlated significantly (p < 0.05) with observed relative PhoA abundances. PstS1 and PstS2 were both observed, yet PstS1 was not differentially more abundant than the control. Phycobilisome protein abundances appeared to be coordinated, and are significantly less abundant in 0.3% Pi than 3% Pi cultures. Also, the central metabolic cell function appears to have shifted towards the production of (NADPH) reducing energy and nucleotide sugars.

Conclusions

This acclimation response bears strong similarity to the previously reported response to nitrogen deprivation within Synechocystis sp. PCC 6803. However, it also demonstrates some characteristics of desiccation stress, such as the regulation of fatty acids and increased abundance of rehydrin in the 3% Pi culture.

Keywords:
Cyanobacteria; iTRAQ; Phosphate acclimation; Phycobilisome; Pentose phosphate pathway; Ribose sugars; Synechocystis