2-DE proteomic analysis of the model cyanobacterium Anabaena variabilis

Cyanobacteria are photosynthetic bacteria capable of producing hydrogen and secondary metabolites with potential pharmaceutical applications. A limited number of cyanobacterial 2-DE proteomic studies have been published, most of which are based on Synechocystis sp. PCC 6803. Here, we report the use of 2-DE, ESI-MS/MS and protein bioinformatics tools to characterize the proteome of Anabaena variabilis ATCC 29413, a heterocystous nitrogen-fixing cyanobacterium that is a model organism for the study of nitrogen fixation. Using a 2-DE workflow that included the use of a detergent-based extraction buffer and 3-10 nonlinear IPG strips resulted in the identification of 254 unique proteins, with significantly better coverage of basic and low-abundance proteins that has been reported in 2-DE analyses of Synechocystis sp. A set of protein bioinformatics tools was employed to provide estimates of protein localization, hydrophobicity, abundance and other properties. The characteristics of the A. variabilis proteins identified in this study were compared against the theoretical proteome for this organism, and more generally within the cyanobacteria, to identify opportunities for further development of 2-DE-based cyanobacterial proteomics.