The TUDOR domain of SMN is an H3K79me1histone mark reader

Abstract

Spinal muscular atrophy is the leading genetic cause of infant mortality and results from depleted levels of functional survival of motor neuron (SMN) protein by either deletion or mutation of theSMN1gene. SMN is characterized by a central TUDOR domain, which mediates the association of SMN with arginine methylated (Rme) partners, such as coilin, fibrillarin, and RNA pol II (RNA polymerase II). Herein, we biochemically demonstrate that SMN also associates with histone H3 monomethylated on lysine 79 (H3K79me1), defining SMN as not only the first protein known to associate with the H3K79me1histone modification but also the first histone mark reader to recognize both methylated arginine and lysine residues. Mutational analyzes provide evidence that SMNTUDORassociates with H3 via an aromatic cage. Importantly, most SMNTUDORmutants found in spinal muscular atrophy patients fail to associate with H3K79me1.