QxxR motif of RNA helicase Me31B shown to be essential for Drosophila female fertility

A preprint posted to bioRxiv on 29 August 2026 reports the functional characterisation of the QxxR motif in Me31B, the Drosophila melanogaster orthologue of the human DEAD-box RNA helicase DDX6. The QxxR motif is conserved across the DEAD-box helicase family, which post-transcriptionally regulates gene expression during animal development, but its precise in vivo role has remained unclear.

The authors generated a Drosophila strain carrying the H333R missense mutation in Me31B — the equivalent of the human pathogenic H372R substitution in DDX6, previously associated with developmental defects. In human DDX6, this substitution converts the QxHR sequence to QxRR within the motif. The preprint reports that flies homozygous for the Drosophila equivalent mutation show severely reduced female fertility and defects in germline development, establishing that the QxxR motif is functionally required for normal oogenesis in vivo.

Because Me31B and DDX6 share high sequence and functional conservation, Drosophila is presented as a tractable in vivo model for understanding the developmental consequences of DDX6 variants. The work adds mechanistic context to the human clinical genetics of DDX6-associated conditions.

This is a preprint and has not undergone peer review.