The interaction of DNA repair factors ASCC2 and ASCC3 is affected by somatic cancer mutations

Abstract

The ASCC3 subunit of the activating signal co-integrator complex is a dual-cassette Ski2-like nucleic acid helicase that provides single-stranded DNA for alkylation damage repair by the α-ketoglutarate-dependent dioxygenase AlkBH3. Other ASCC components integrate ASCC3/AlkBH3 into a complex DNA repair pathway. We mapped and structurally analyzed interacting ASCC2 and ASCC3 regions. The ASCC3 fragment comprises a central helical domain and terminal, extended arms that clasp the compact ASCC2 unit. ASCC2–ASCC3 interfaces are evolutionarily highly conserved and comprise a large number of residues affected by somatic cancer mutations. We quantified contributions of protein regions to the ASCC2–ASCC3 interaction, observing that changes found in cancers lead to reduced ASCC2–ASCC3 affinity. Functional dissection of ASCC3 revealed similar organization and regulation as in the spliceosomal RNA helicase Brr2. Our results delineate functional regions in an important DNA repair complex and suggest possible molecular disease principles.

Structural basis for clearing of ribosome collisions by the RQT complex

“…9b, c ). This domain of Cue3 is similar to the X-ray structure of the human homolog ASCC2 in complex with the N-terminal domain of ASCC3 (Slh1) which we do not observe 37 . The predicted ubiquitin-binding CUE domain (298-360), a linked four-helix bundle (468-541), and the ultimate C-terminus (542-624) are not visible in our structures, most likely due to their high flexibility.…”

“…9a ). In agreement with this, a contribution of both cassettes was shown for DNA unwinding activity of the human homolog ASCC3 43 , although earlier studies assigned this activity to either the N− 37 or the C-terminal cassette 44 . Since we found that single Walker mutations in both the NTC and the CTC abolish RQT activity (Fig.…”

Unresolved stalled ribosome complexes restrict cell-cycle progression after genotoxic stress

“…ASCC3 contains two Ski2-like helicase domains, but only the N-terminal domain is active ( Jia et al., 2020 ). Since RNA helicases are ATP-gated RBPs, we investigated the link between ASCC3 RNA binding and helicase activity.…”

“…The GKT motif in the N-terminal helicase domain of ASCC3 is essential for ATP binding and RNA-helicase activity ( Jia et al., 2020 ). Therefore, we mutated the N-terminal GKT motif and determined the effect on ASCC3 RNA binding in vivo ( Figure 1 E).…”

Identification of Prognostic and Chemopredictive microRNAs for Non-Small-Cell Lung Cancer by Integrating SEER-Medicare Data

“…Hotspot mutations of SF3B1 are associated with cancer and affect alternative splicing by promoting alternative branchpoint usage [ 53 ]. The affinity between DNA repair factors ASCC2 and ASCC3 is reduced by cancer mutations [ 54 ]. Depletion of SNRPE or SNRPD1 led to autophagy and a marked reduction of cell viability in breast, lung, and melanoma cancer cell lines, accompanied by a deregulation of the mTOR pathway [ 55 ].…”