Publication details
The Phenotype of Physcomitrium patens SMC6 Mutant with Interrupted Hinge Interactions
| Authors | |
|---|---|
| Year of publication | 2025 |
| Type | Article in Periodical |
| Magazine / Source | Genes |
| MU Faculty or unit | |
| Citation | |
| web | https://www.mdpi.com/2073-4425/16/9/1091 |
| Doi | https://doi.org/10.3390/genes16091091 |
| Keywords | SMC5/6; hinge domain; protein-protein interactions; DSB repair; mutagenesis; gene targeting; rDNA stability; protonemata development; Physcomitrium patens SMC5/6 |
| Description | Background/Objectives: The Structural Maintenance of Chromosomes (SMC) proteins form essential heterocomplexes for the preservation of DNA structure and its functions, and hence cell viability. The SMC5/6 dimer is assembled by direct interactions of ATP heads via the kleisin NSE4 bridge and by SMC hinges. The structure might be interrupted by a single point mutation within a conserved motif of the SMC6-hinge. We describe the phenomena associated with the impairment of the SMC5/6 complex with morphology, repair of DNA double strand breaks (DSB), mutagenesis, recombination and gene targeting (GT) in the moss Physcomitrium patens (P. patens). Methods: Using CRISPR/Cas9-directed oligonucleotide replacement, we have introduced two close G to R point mutations in the hinge domain of SMC6 of P. patens and show that both mutations are not toxic and allow viability of mutant lines. Results: The G514R mutation fully prevents the interaction of SMC6 not only with SMC5, but also with NSE5 and NSE6, while the mutation at G517R has no effect. The Ppsmc6_G514R line has aberrant morphology, spontaneous and bleomycin-induced mutagenesis, and maintenance of the number of rDNA copies. The most unique feature is the interference with gene targeting (GT), which is completely abolished. In contrast, the Ppsmc6_G517R line is close to WT in many aspects. Surprisingly, both mutations have no direct effect on the rate of DSB repair in dividing and differentiated cells. Conclusions: Abolished interactions of SMC6 with SMC5 and NSE5,6 partners, which allow DSB repair, but impair other repair and recombination functions, suggests also regulatory role for SMC6. |
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