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CryoEM structure of Abo1 Walker B (E372Q) mutant hexamer - ATP complex
Structural highlights
FunctionATD2_SCHPO ATPase histone chaperone which facilitates loading of histone H3-H4 onto DNA in an ATP-dependent manner (PubMed:31848341, PubMed:33658433). Plays a genome-wide role in nucleosome organization and establishment of chromatin (PubMed:26582768, PubMed:31848341). Also plays a role in heterochromatin assembly by stabilizing recruitment of the histone methyltransferase clr4 to methylated histone H3, to promote the transition from H3K9me2 to H3K9me3 (PubMed:32269268).[1] [2] [3] [4] Publication Abstract from PubMedThe fundamental unit of chromatin, the nucleosome, is an intricate structure that requires histone chaperones for assembly. ATAD2 AAA+ ATPases are a family of histone chaperones that regulate nucleosome density and chromatin dynamics. Here, we demonstrate that the fission yeast ATAD2 homolog, Abo1, deposits histone H3-H4 onto DNA in an ATP-hydrolysis-dependent manner by in vitro reconstitution and single-tethered DNA curtain assays. We present cryo-EM structures of an ATAD2 family ATPase to atomic resolution in three different nucleotide states, revealing unique structural features required for histone loading on DNA, and directly visualize the transitions of Abo1 from an asymmetric spiral (ATP-state) to a symmetric ring (ADP- and apo-states) using high-speed atomic force microscopy (HS-AFM). Furthermore, we find that the acidic pore of ATP-Abo1 binds a peptide substrate which is suggestive of a histone tail. Based on these results, we propose a model whereby Abo1 facilitates H3-H4 loading by utilizing ATP. Structural basis of nucleosome assembly by the Abo1 AAA+ ATPase histone chaperone.,Cho C, Jang J, Kang Y, Watanabe H, Uchihashi T, Kim SJ, Kato K, Lee JY, Song JJ Nat Commun. 2019 Dec 17;10(1):5764. doi: 10.1038/s41467-019-13743-9. PMID:31848341[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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