6wlg
From Proteopedia
Ints3 C-terminal Domain
Structural highlights
Function[INT3_HUMAN] Component of the Integrator complex. The Integrator complex is involved in the small nuclear RNAs (snRNA) U1 and U2 transcription and in their 3'-box-dependent processing. The Integrator complex is associated with the C-terminal domain (CTD) of RNA polymerase II largest subunit (POLR2A) and is recruited to the U1 and U2 snRNAs genes.[1] [2] Component of the SOSS complex, a multiprotein complex that functions downstream of the MRN complex to promote DNA repair and G2/M checkpoint. The SOSS complex associates with single-stranded DNA at DNA lesions and influences diverse endpoints in the cellular DNA damage response including cell-cycle checkpoint activation, recombinational repair and maintenance of genomic stability. The SOSS complex is required for efficient homologous recombination-dependent repair of double-strand breaks (DSBs) and ATM-dependent signaling pathways. In the SOSS complex, it is required for the assembly of the complex and for stabilization of the complex at DNA damage sites.[3] [4] Publication Abstract from PubMedProper repair of damaged DNA is critical for the maintenance of genome stability. A complex composed of Integrator subunit 3 (Ints3), single-stranded DNA-binding protein 1 (SSB1) and SSB-interacting protein 1 (SSBIP1) is required for efficient homologous recombination-dependent repair of double-strand breaks (DSBs) and ataxia-telangiectasia mutated (ATM)-dependent signaling pathways. It is known that in this complex the Ints3 N-terminal domain scaffolds SSB1 and SSBIP1. However, the molecular basis for the function of the Ints3 C-terminal domain remains unclear. Here, we present the crystal structure of the Ints3 C-terminal domain, uncovering a HEAT-repeat superhelical fold. Using structure and mutation analysis, we show that the C-terminal domain exists as a stable dimer. A basic groove and a cluster of conserved residues on two opposite sides of the dimer bind single-stranded RNA/DNA (ssRNA/ssDNA) and Integrator complex subunit 6 (Ints6), respectively. Dimerization is required for nucleic acid binding, but not for Ints6 binding. Additionally, in vitro experiments using HEK 293T cells demonstrate that Ints6 interaction is critical for maintaining SSB1 protein level. Taken together, our findings establish the structural basis of a multifunctional Ints3 C-terminal module, allowing us to propose a novel mode of nucleic acid recognition by helical repeat protein and paving the way for future mechanistic studies. Structural basis for multifunctional roles of human Ints3 C-terminal domain.,Li J, Ma X, Banerjee S, Baruah S, Schnicker NJ, Roh E, Ma W, Liu K, Bode AM, Dong Z J Biol Chem. 2020 Nov 23. pii: RA120.016393. doi: 10.1074/jbc.RA120.016393. PMID:33229437[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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