5ja4
From Proteopedia
Crystal structure of human TONSL and MCM2 HBDs binding to a histone H3-H4 tetramer
Structural highlights
Function[TONSL_HUMAN] Component of the MMS22L-TONSL complex, a complex that stimulates the recombination-dependent repair of stalled or collapsed replication forks. The MMS22L-TONSL complex is required to maintain genome integrity during DNA replication by promoting homologous recombination-mediated repair of replication fork-associated double-strand breaks. It may act by mediating the assembly of RAD51 filaments on ssDNA. Within the complex, may act as a scaffold.[1] [2] [3] [4] [MCM2_HUMAN] Acts as component of the MCM2-7 complex (MCM complex) which is the putative replicative helicase essential for 'once per cell cycle' DNA replication initiation and elongation in eukaryotic cells. The active ATPase sites in the MCM2-7 ring are formed through the interaction surfaces of two neighboring subunits such that a critical structure of a conserved arginine finger motif is provided in trans relative to the ATP-binding site of the Walker A box of the adjacent subunit. The six ATPase active sites, however, are likely to contribute differentially to the complex helicase activity. Required for the entry in S phase and for cell division.[5] Publication Abstract from PubMedAfter DNA replication, chromosomal processes including DNA repair and transcription take place in the context of sister chromatids. While cell cycle regulation can guide these processes globally, mechanisms to distinguish pre- and post-replicative states locally remain unknown. Here we reveal that new histones incorporated during DNA replication provide a signature of post-replicative chromatin, read by the human TONSL-MMS22L homologous recombination complex. We identify the TONSL ankyrin repeat domain (ARD) as a reader of histone H4 tails unmethylated at K20 (H4K20me0), which are specific to new histones incorporated during DNA replication and mark post-replicative chromatin until the G2/M phase of the cell cycle. Accordingly, TONSL-MMS22L binds new histones H3-H4 both before and after incorporation into nucleosomes, remaining on replicated chromatin until late G2/M. H4K20me0 recognition is required for TONSL-MMS22L binding to chromatin and accumulation at challenged replication forks and DNA lesions. Consequently, TONSL ARD mutants are toxic, compromising genome stability, cell viability and resistance to replication stress. Together, these data reveal a histone-reader-based mechanism for recognizing the post-replicative state, offering a new angle to understand DNA repair with the potential for targeted cancer therapy. H4K20me0 marks post-replicative chromatin and recruits the TONSL-MMS22L DNA repair complex.,Saredi G, Huang H, Hammond CM, Alabert C, Bekker-Jensen S, Forne I, Reveron-Gomez N, Foster BM, Mlejnkova L, Bartke T, Cejka P, Mailand N, Imhof A, Patel DJ, Groth A Nature. 2016 Jun 30;534(7609):714-8. PMID:27338793[6] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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