Intrinsically disordered regions regulate both catalytic and non-catalytic activities of the MutLα mismatch repair complex

Abstract

Intrinsically disordered regions (IDRs) are present in at least 30% of the eukaryotic proteome and are enriched in chromatinassociated proteins. Using a combination of genetics, biochemistry, and single-molecule biophysics, we characterize how IDRs regulate the functions of the yeast MutLa (Mlh1-Pms1) mismatch repair (MMR) complex. Shortening or scrambling the IDRs in both subunits ablates MMR in vivo. Mlh1-Pms1 complexes with shorter IDRs that disrupt MMR retain wild-type DNA binding affinity but are impaired for diffusion on both naked and nucleosome-coated DNA. Moreover, the IDRs also regulate the ATP hydrolysis and nuclease activities that are encoded in the structured N-and C-terminal domains of the complex. This combination of phenotypes underlies the catastrophic MMR defect seen with the mutant MutLa in vivo. More broadly, this work highlights an unanticipated multi-functional role for IDRs in regulating both facilitated diffusion on chromatin and nucleolytic processing of a DNA substrate.

Disorder in a two-domain neuronal Ca2+-binding protein regulates domain stability and dynamics using ligand mimicry

“…The recoverin tail is very different and still has about the same effect on stability as the wild-type, re-enforcing the idea that tail dynamics are critical. Nevertheless, as our mutational experiments reveal, the sequence has an influence on tail functionality, although not as pronounced as seen for MutLα (Mlh1-Pms1) mismatch repair (MMR) complex, where scrambling ablated function [49], but similar to the tail-function in CIB1, where the tail was displaced upon ligand binding [44]. Finally, it is possible that the tail of NCS-1 may also affect Ca 2+ -binding, as observed for a calmodulin variant from rice [43], but this remains to be addressed.…”