First observation by fluorescence polarization of complexation between mRNA and the natural polysaccharide schizophyllan

Schizophyllan is a natural β-(1 → 3)-D-glucan that exists as a triple helix in H₂O and as a single chain in dimethylsulfoxide (DMSO) or basic solution (pH >13). As we have already reported, when a homopolynucleotide (e.g., poly(dA), poly(A), or poly(C)) is added to a schizophyllan/DMSO solution, and, subsequently, DMSO is exchanged for H ₂O, the single chain of schizophyllan forms a complex with the polynucleotide. Since eukaryotic mRNAs have poly(A) tails, we hypothesized that schizophyllan can bind to mRNA by interacting with this tail. However, we have not yet observed complexation between schizophyllan and mRNA after exchanging DMSO for H₂O. In this report, we show that the complexation can be accelerated when the solution pHis changed from 13 to 7-8 in the presence of schizophyllan and polynucleotides. By this approach, we found that schizophyllan forms a complex with a yeast mRNA.