Identification of surface polysaccharides in akinetes, heterocysts and vegetative cells of Anabaena cylindrica using fluorescein-labeled lectins
In response to environmental changes, Anabaena cylindrica differentiate three cell types: vegetative cells for photosynthesis, heterocysts for nitrogen fixation, and akinetes for stress survival. Cell-surface polysaccharides play important roles in cyanobacterial ecophysiology. In this study, specific cell-surface sugars were discovered in heterocysts, akinetes and vegetative cells of A. cylindrica using 20 fluorescein-labeled lectins. Both N-acetylglucosamine-binding lectins WGA and succinylated WGA bound specifically to the vegetative cells. Akinetes bound to three mannose-binding lectins (LCA, PSA, and ConA), and one of the galactose-binding lectins (GSL-I). Heterocyst also bound to ConA. However, the heterocysts in all4388 mutant of Anabaena sp. PCC 7120, in which the putative polysaccharide export protein gene all4388 was disrupted, exhibited diminished binding to ConA. Identification of distinct cell-surface sugar helped us to understand the role of polysaccharide for each cell type. Fluorescence-activated cell sorting may be applicable in isolating each cell type for comparative “omics” studies among the three cell types.
KeywordsCyanobacteria Lectins Polysaccharides Spore Heterocyst Nitrogen fixation
Wheat germ agglutinin
Phaseolus vulgaris erythroagglutinin
Len culinaris lectin
Pisum sativum agglutinin
Griffonia Simplicifolia lectin I
The authors would like to thank Dr. Peter Wolk for providing the all4388-knockout mutant FQ1595, Dr. Brözel for his advice on manuscript preparation, Dilkaran Singh’s graphing help, and acknowledge use of the South Dakota State University Functional Genomics Core Facility supported in part by NSF/EPSCoR Grant No. 0091948 and by the State of South Dakota. This work was partially supported by USDA-NIFA GRANT11665597 (to R. Z.), and by the South Dakota Agricultural Experiment Station.
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Conflict of interest
The authors declare that they have no conflict of interest.
Supplementary material 1 (AVI 149313 KB)
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