%0 Journal Article
%T Comparative quantitative proteomics of prochlorococcus ecotypes to a decrease in environmental phosphate concentrations
%A Matthew A Fuszard
%A Phillip C Wright
%A Catherine A Biggs
%J Aquatic Biosystems
%D 2012
%I BioMed Central
%R 10.1186/2046-9063-8-7
%X Prochlorococcus strains representing both high light (HL) (MIT9312) and low light (LL) (NATL2A and SS120) ecotypes were grown identically in phosphate depleted media (10 ¦ÌM Pi). The three strains displayed marked differences in cellular protein expression, as determined by high throughput large scale quantitative proteomic analysis. The only strain to demonstrate a significantly different growth rate under reduced phosphate conditions was MIT9312. Additionally, there was a significant increase in phosphate-related proteins such as PhoE (> 15 fold increase) and a depression of the Rubisco protein RbcL abundance in this strain, whereas there appeared to be no significant change within the LL strain SS120.This differential response between ecotypes highlights the relative importance of phosphate availability to each strain and from these results we draw the conclusion that the expression of phosphate acquisition mechanisms are activated at strain specific phosphate concentrations.Within marine oligotrophic systems, such as central subtropical gyres, orthophosphate (Pi) is a crucial macronutrient governing microbial population densities, particularly within the well-lit surface waters of the euphotic zone [1-3]. The principal photosynthetic organism numerically dominating these areas is Prochlorococcus, which is estimated to represent about 50% of all photosynthetic activity within them [4,5]. Prochlorococcus has been broadly delineated into two clades, or ecotypes, high light (HL) and low light (LL) based upon the ratios of divinylchlorophylla and b within their light harvesting apparatuses and as such their assumed depth within the water column [6,7]. Further clade subdivisions have been implemented through phylogenetic analyses of 16S rRNA sequences [8]. As a taxon, Prochlorococcus is characterised by its small size (~ 1 ¦Ìm3), and significantly reduced genomes which ranges from 1.64 Mbps (the HL strain MIT9301) to 2.68 Mbps (the LL strain MIT9303) [9]. This diminishe
%K Prochlorococcus
%K PstS
%K PhoA
%K PhoE
%K Growth
%K Phosphate
%U http://www.aquaticbiosystems.org/content/8/1/7