The Nuclear Actin-related Protein of Saccharomyces cerevisiae, Arp4, Directly Interacts with the Histone Acetyltransferase Esa1p

Ten actin-related proteins are known in Saccharomyces cerevisiae, classified into Arps1-10 according to their relatedness to actin. Arp4, a nuclear protein, essential for viability of S. cerevisiae, is a component of at least three chromatin-modifying complexes, one of which is the histone acetyltransferase (HAT) complex NuA4. Since recent data point to a role for Arp4 in the recruitment to specific sites of interaction, we tested if Arp4 directly interacts with the HAT Esa1p that is the catalytic subunit of NuA4. We observed that Arp4 directly binds to Esa1p, whereas Act1p, which is also a component of the NuA4 complex, does not interact with Esa1p. The interaction of Arp4 and Esa1p was not abolished by a deletion of one or both of the specific insertions present in the ARP4 gene. We propose that the interaction of Arp4 with Esa1p is crucial for proper functioning and targeting of the NuA4 complex.