Biochemical characterization of the meiosis-essential yet evolutionarily divergent topoisomerase VIB-like protein MTOPVIB from Arabidopsis thaliana

Hsin-Wen Chen (1) , Hsin-Yi Yeh (1) , Chih-Chiang Chang (1) , Wei-Chen Kuo (1) , Sheng-Wei Lin (2) , Nathalie Vrielynck (3) , Mathilde Grelon (3) , Nei-Li Chan (1) , Peter Chi (1, 2)

1 NTU - National Taiwan University [Taiwan]
2 IBC Sinica - Institute of Biological Chemistry
3 IJPB - Institut Jean-Pierre Bourgin

Formation of programmed DNA double-strand breaks is essential for initiating meiotic recombination. Genetic studies on Arabidopsis thaliana and Mus musculus have revealed that assembly of a type IIB topoisomerase VI (Topo VI)-like complex, composed of SPO11 and MTOPVIB, is a prerequisite for generating DNA breaks. However, it remains enigmatic if MTOPVIB resembles its Topo VI subunit B (VIB) ortholog in possessing robust ATPase activity, ability to undergo ATP-dependent dimerization, and activation of SPO11-mediated DNA cleavage. Here, we successfully prepared highly pure A. thaliana MTOPVIB and MTOPVIB-SPO11 complex. Contrary to expectations, our findings highlight that MTOPVIB differs from orthologous Topo VIB by lacking ATP-binding activity and independently forming dimers without ATP. Most significantly, our study reveals that while MTOPVIB lacks the capability to stimulate SPO11-mediated DNA cleavage, it functions as a bona fide DNA-binding protein and plays a substantial role in facilitating the dsDNA binding capacity of the MOTOVIB-SPO11 complex. Thus, we illustrate mechanistic divergence between the MTOPVIB-SPO11 complex and classical type IIB topoisomerases.

Domaines: Génétique des plantes

Hsin-Wen Chen, Hsin-Yi Yeh, Chih-Chiang Chang, Wei-Chen Kuo, Sheng-Wei Lin, et al.. Biochemical characterization of the meiosis-essential yet evolutionarily divergent topoisomerase VIB-like protein MTOPVIB from Arabidopsis thaliana. Nucleic Acids Research, 2024, ⟨10.1093/nar/gkae181⟩. ⟨hal-04569399⟩