Assembly stoichiometry of bacterial selenocysteine synthase and SelC (tRNAsec)

► SelA-tRNAsec binding stoichiometry of five tRNAsec per SelA decamer is incorrect. ► Direct and reverse fluorescence anisotropy show a stoichiometry of one 1:1. ► EM symmetry analysis shows a D5 pointgroup symmetry for the SelA-tRNAsec complex. ► The correct stoichiometric ratio of 1:1 SelA-tRNAsec is revealed.