Analyzing the Akinete Protein of the Harmful Freshwater Cyanobacterium, Dolichospermum circinale

Abstract

Akinete is a survival structure in cyanobacteria that has overcome unfavorable environmental conditions and influences their perennial blooms in the freshwater system. However, the akinete cellular and biochemical properties are insufficiently explored. We analyzed the akinete structure, as well as akinete-specific proteins and their amino acid sequence. Akinetes of Dolichospermum circinale were produced from their vegetative cells isolated from the North Han River, Korea. The akinete protein was obtained using electrophoresis, and utilizing its amino acid sequences, its antibody-binding reaction potential (ig-score) was quantified. Akinete protein masses were 17 kDa–180 kDa, and the akinete protein mass was 110 kDa. The ig score was high (average 5.0121 points) in the first half of the amino acid sequence, indicating a β-turn form. The amino acid sequence, having over 50% homology with the D. circinale akinete protein, was not present in GenBank. The homology of the D. circinale akinete-specific protein was very low (9.8%) compared to that of Anabaena variabilis, indicating that its composition was substantially different, even among phylogenetically close taxa. To the best of our knowledge, this is the first report on the D. circinale akinete protein and its amino acid sequence, with preliminary information for their practical application for detecting akinetes in freshwater systems.