The five RAD51 paralogs are known to be required for homologous recombination and maintenance of genomic stability. Indeed, RAD51C interacts with RAD51B, RAD51D, XRCC2 and XRCC3 in two different complexes that play a role in homologous recombination. Miller et al studied the interaction between RAD51B and D (and also XRCC3) with deletion mutants. These authors found that Rad51C1-285 (includes β-strands 1-5) or Rad51C285-376 (includes β-strands 6-9) did not bind RAD51B. So, a complete beta-sheet is important in maintaining the overall fold of the protein. Moreover, the missense variant p.Arg312Trp (ß-strand 6) has been shown to impair RAD51C function (Gayarre et al 2017). Both studies indicate that this protein region is essential for RAD51C function so that transcripts lacking any of the β-strands, such as ▼(E6q4)-a, ▼(E6q4)-b, Δ(E7), Δ(E8) or the in-frame isoform Δ(E5), is probably deleterious. - We have modified this part, adding several sentences to clarify it. Lines 270-277: “ The integrity of the β-sheet is important in maintaining the overall fold of the RAD51C protein and the interaction with RAD51B, so that alterations of any ß-strand of RAD51C should be considered deleterious [33]. Further, structural features (the order of the ß--strands in space is not the same as their order in sequence) predict that proteins lacking any single b-strand would fail to form the ß--sheet resulting in a collapse of the protein core and misfolding of the protein [33]. Moreover, the missense variant p.Arg312Trp (ß-strand 6) has been shown to impair RAD51C function [34]. Altogether these data,…” 3-
Lines 250-251 and 263-265– In these lines the authors discuss transcripts in which the encoded proteins lack some beta strands. The lack of these protein structures are used as evidence to support pathogenicity. It is not clear from the text how lack of these beta strands is predicted to impact protein function. Is there evidence from another source that these beta strands are critical to protein function and that their loss is deleterious (rather than resulting in normal or slightly reduced protein activity)?