The SNF2 ATPase-independent function of the INO80 chromatin remodeler [RNA-seq]

In the multi-subunit INO80 chromatin-remodeling complex, all the auxiliary subunits assemble on three distinct domains of the catalytic chromatin remodeler INO80, which are N-terminal domain, HSA domain, and ATPase domain. While the ATPase and HSA domains and the auxiliary subunits assembling on the domains are known to be responsible for ATP hydrolysis and chromatin remodeling, it is largely unknown how the auxiliary subunits assembling on the INO80 N-terminal domain regulate the chromatin status. We identify both conserved and non-conserved auxiliary subunits of the INO80 complex in Arabidopsis thaliana. All the auxiliary subunits assemble on the conserved N-terminal domain, HSA domain, and ATPase domain of INO80 in Arabidopsis. While the auxiliary subunits assembling on the INO80 ATPase domain are required for the ATPase-dependent function, the INO80 N-terminal domain and the auxiliary subunits assembling on the domain can regulate gene expression and development even when the ATPase domain is absent, suggesting that INO80 has an ATPase-independent role. Furthermore, we find that a subclass of the COMPASS histone H3K4 methyltransferase complexes assemble on the INO80 N-terminal domain in the INO80 complex and function together with the other auxiliary subunits assembling on the INO80 N-terminal domain, thereby facilitating the ATPase-independent function. This study suggests that the conserved chromatin remodeler INO80 has an ATPase-independent role and demonstrates that the auxiliary subunits assembling on the INO80 N-terminal domain are required for the ATPase-independent role. Overall design: Examination of the mRNA expression of wild type, five mutants, and three transgenic lines grown under long day or short day conditions.