An iTRAQ-based quantitative analysis to elaborate the proteomic response of Nostoc sp PCC 7120 under N2 fixing conditions

Nostoc sp. PCC 7120 is an oxygen-evolving photoautotrophic N-2 fixing filamentous cyanobacterium. Upon nitrogen starvation, a range of processes are initiated, such as differentiation of the heterocysts, specific cells where N-2 fixation takes place. We have characterized and quantified the proteome of the Nostoc sp. PCC 7120 wild-type strain grown under N-2 fixing and non-N-2 fixing conditions. To assess global proteome changes in response to environmental changes, measurements were made using the quantitative proteomics tool, iTRAQ, on a whole cell digest. From this approach, a total of 486 different proteins was accurately identified across 2 biological replicate experiments, where 226 identifications contained 2 or more distinct peptides. Results of metabolic regulation will be discussed to demonstrate that proteomics represents an important tool for the development of heterocystous cyanobacteria for future biological H-2 production.