6j8y
Crystal structure of the human RAD9-HUS1-RAD1-RHINO complex
Structural highlights
FunctionRAD9A_HUMAN Component of the 9-1-1 cell-cycle checkpoint response complex that plays a major role in DNA repair. The 9-1-1 complex is recruited to DNA lesion upon damage by the RAD17-replication factor C (RFC) clamp loader complex. Acts then as a sliding clamp platform on DNA for several proteins involved in long-patch base excision repair (LP-BER). The 9-1-1 complex stimulates DNA polymerase beta (POLB) activity by increasing its affinity for the 3'-OH end of the primer-template and stabilizes POLB to those sites where LP-BER proceeds; endonuclease FEN1 cleavage activity on substrates with double, nick, or gap flaps of distinct sequences and lengths; and DNA ligase I (LIG1) on long-patch base excision repair substrates. The 9-1-1 complex is necessary for the recruitment of RHNO1 to sites of double-stranded breaks (DSB) occurring during the S phase. RAD9A possesses 3'->5' double stranded DNA exonuclease activity. Its phosphorylation by PRKCD may be required for the formation of the 9-1-1 complex.[1] [2] Publication Abstract from PubMedDNA clamp, a highly conserved ring-shaped protein, binds double-stranded DNA within its central pore. Also, DNA clamp interacts with various nuclear proteins on its front, thereby stimulating their enzymatic activities and biological functions. It has been assumed that the DNA clamp is a functionally single-faced ring from bacteria to human. Here, we report the crystal structure of the hetero-trimeric RAD9-RAD1-HUS1 (9-1-1) checkpoint clamp bound to a peptide of RHINO, a recently identified cancer-related protein that interacts with 9-1-1 and promotes activation of DNA damage checkpoint. This is the first structure of 9-1-1 bound to its partner. The structure reveals that RHINO is unexpectedly bound to the edge and around the back of 9-1-1 ring through specific interactions with RAD1 subunit of 9-1-1. Our finding indicates that 9-1-1 is a functionally double-faced DNA clamp. Structure of the RAD9-RAD1-HUS1 checkpoint clamp bound to RHINO sheds light on the other side of the DNA clamp.,Hara K, Iida N, Tamafune R, Ohashi E, Sakurai H, Ishikawa Y, Hishiki A, Hashimoto H J Biol Chem. 2019 Nov 27. pii: AC119.011816. doi: 10.1074/jbc.AC119.011816. PMID:31776186[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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