Arabidopsis cysteine proteinase inhibitor AtCYSb interacts with a Ca2+-dependent nuclease, AtCaN2

Abstract Plant cysteine proteinase inhibitors (cystatins) play important roles in plant defense mechanisms. Some proteins that interact with cystatins may defend against abiotic stresses. Here, we showed that AtCaN2, a Ca 2+ -dependent nuclease in Arabidopsis , is transcribed in senescent leaves and stems and interacts with an Arabidopsis cystatin (AtCYSb) in a yeast two-hybrid screen. The interaction between AtCYSb and AtCaN2 was confirmed by in vitro pull-down assay and bimolecular fluorescence complementation. Agarose gel electrophoresis showed that the nuclease activity of AtCaN2 against λDNA was inhibited by AtCYSb, which suggests that AtCYSb regulates nucleic acid degradation in cells. Structured summary of protein interactions AtCYSb and AtCaN2 physically interact by bimolecular fluorescence complementation ( View interaction ) AtCYSb binds to AtCaN2 by pull down ( View interaction ) AtCYSb physically interacts with AtCaN2 by two hybrid ( View interaction )