The SWR1 complex is involved in chromatin-remodeling by promoting the the ATP-dependent exchange of histone H2A for the H2A variant HZT1 in Saccharomyces cerevisiae or H2AZ in mammals. The SWR1 chromatin-remodeling complex is composed of at least 14 subunits and has a molecular mass of about 1.2 to 1.5 MDa. In S. cerevisiae there are core conserved subunits (ATPase; Swr1,RuvB-like; Rvb1 and Rvb2, Actin; Act1, Actin-related: Arp4 and Arp6, YEATS protein; [1]) and non-conserved subunits (Vps71 (Swc6), Vps72 (Swc2), Swc3, Swc4, Swc5, Swc7, Bdf1 [2]). Seven of the SWR1 subunits are involved in maintaining complex integrity and H2AZ histone replacement activity: Swr1, Swc2, Swc3, Arp6, Swc5, Yaf9 and Swc6. Arp4 is required for the association of Bdf1, Yaf9, and Swc4 and Arp4 is also required for SWR1 H2AZ histone replacement activity in vitro. Furthermore the N-terminal region of the ATPase Swr1 provides the platform upon which Bdf1, Swc7, Arp4, Act1, Yaf9 and Swc4 associate [3]. It also contains an additional H2AZ-H2B specific binding site, distinct from the binding site of the Swc2 subunit [4]. In eukaryotes the deposition of variant histones into nucleosomes by the chromatin-remodeling complexes such as the SWR1 and INO80 complexes have many crucial functions including the control of gene regulation and expression, checkpoint regulation, DNA replication and repair, telomere maintenance and chromosomal segregation and as such represent critical components of pathways that maintain genomic integrity. This entry represents the subunit Swc7; the smallest subunit of the SWR1 complex. Swc7 is not required for H2AZ binding. It associates with the N terminus of Swr1, and the association of Bdf1 requires Swc7, Yaf9, and Arp4 [3].

1: YEATS domain proteins: a diverse family with many links to chromatin modification and transcription. Schulze JM, Wang AY, Kobor MS; Biochem Cell Biol. 2009;87:65-75. PMID:19234524

2: Chromatin remodelling beyond transcription: the INO80 and SWR1 complexes. Morrison AJ, Shen X; Nat Rev Mol Cell Biol. 2009;10:373-384. PMID:19424290

3: Swc2 is a widely conserved H2AZ-binding module essential for ATP-dependent histone exchange. Wu WH, Alami S, Luk E, Wu CH, Sen S, Mizuguchi G, Wei D, Wu C; Nat Struct Mol Biol. 2005;12:1064-1071. PMID:16299513

4: N terminus of Swr1 binds to histone H2AZ and provides a platform for subunit assembly in the chromatin remodeling complex. Wu WH, Wu CH, Ladurner A, Mizuguchi G, Wei D, Xiao H, Luk E, Ranjan A, Wu C; J Biol Chem. 2009;284:6200-6207. PMID:19088068