New feature of hMEIOB and hSPATA22 binding to ssDNA from a single-molecule perspective

• hMEIOB alone exhibits low ssDNA-binding affinity and stability, whereas hSPATA22 binds ssDNA faster and more stably, promoting ssDNA condensation. • The hMEIOB-hSPATA22 heterodimer displays strong binding affinity and stability to ssDNA, and multiple heterodimers spontaneously aggregate in vitro. • The human RPA complex weakens the binding affinity of hMEIOB, hSPATA22, and the heterodimer to ssDNA, while also binding to hSPATA22 and the heterodimer, suggesting a regulatory role in meiotic recombination. • This study provides the first single-molecule characterization of hMEIOB and hSPATA22 binding to ssDNA, offering insights into species-specific differences and potential therapeutic targets for male infertility.