Comparative proteomics reveals that a saxitoxin-producing and a nontoxic strain of Anabaena circinalis are two different ecotypes.
In Australia, saxitoxin production is restricted to the cyanobacterial species Anabaena circinalis and is strain-dependent. We aimed to characterize a saxitoxin-producing and nontoxic strain of A. circinalis at the proteomic level using iTRAQ. Seven proteins putatively involved in saxitoxin biosynthesis were identified within our iTRAQ experiment for the first time. The proteomic profile of the toxic A. circinalis was significantly different from the nontoxic strain, indicating that each is likely to inhabit a unique ecological niche. Under control growth conditions, the saxitoxin-producing A. circinalis displayed a higher abundance of photosynthetic, carbon fixation and nitrogen metabolic proteins. Differential abundance of these proteins suggests a higher intracellular C:N ratio and a higher concentration of intracellular 2-oxoglutarate in our toxic strain compared with the nontoxic strain. This may be a novel site for posttranslational regulation because saxitoxin biosynthesis putatively requires a 2-oxoglutarate-dependent dioxygenase. The nontoxic A. circinalis was more abundant in proteins, indicating cellular stress. Overall, our study has provided the first insight into fundamental differences between a toxic and nontoxic strain of A. circinalis, indicating that they are distinct ecotypes.
School of Science and Health, University of Western Sydney , Campbelltown, NSW 2560, Australia.
Paul M
PM
D'Agostino
Xiaomin
X
Song
Brett A
BA
Neilan
Michelle C
MC
Moffitt
D017033:Anabaena / Q000145:classification / Q000235:genetics* / Q000378:metabolism / Q000472:pathogenicity*; D001426:Bacterial Proteins / Q000032:analysis* / Q000235:genetics / Q000378:metabolism; D060146:Ecotype; D015964:Gene Expression Regulation, Bacterial; D007656:Ketoglutaric Acids / Q000378:metabolism; D013058:Mass Spectrometry / Q000379:methods; D058977:Molecular Sequence Annotation; D009584:Nitrogen / Q000378:metabolism; D010455:Peptides / Q000032:analysis; D010788:Photosynthesis / Q000235:genetics; D010802:Phylogeny; D040901:Proteomics; D012530:Saxitoxin / Q000096:biosynthesis*; D013194:Staining and Labeling / Q000379:methods; D014774:Virulence
D001426:Bacterial Proteins; D007656:Ketoglutaric Acids; D010455:Peptides; D012530:Saxitoxin; D009584:Nitrogen