Structural basis of dsRNA unwinding by essential RNA helicases MLE/DHX9 and their co-factors

• Applicant: Professor Dr. Janosch Hennig
• Subject Area: Structural Biology ; Biochemistry ; Biophysics ; Developmental Biology
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 533362036

RNA helicases play crucial roles in various cellular processes involving RNA by processing, unwinding, or remodeling RNA molecules in an ATP-dependent manner. Despite extensive research and high-resolution structures, the factors determining RNA specificity of RNA helicases and the functions of auxiliary domains remain poorly understood. Recently, we discovered that the RNA helicase maleless (MLE) undergoes autoregulation through its N-terminal double-stranded RNA binding domain, which is essential for unwinding the long non-coding RNA RoX2 and for dosage compensation in Drosophila. MLE's remodeling of RoX2 triggers the assembly of the dosage compensation complex (DCC). The rate-limiting component of the DCC, MSL2, subsequently binds to RoX2, leading to specific targeting of the X chromosome chromatin. Our recent study demonstrated that interfering with MLE's intricate RNA unwinding mechanism has lethal consequences for male flies. In our proposed research, we aim to unravel the next step in dosage compensation: understanding how MSL2 binds to RoX2, the role of the first double-stranded RNA binding domain, the involvement of the co-factor Unr, and the dependence of this process on RoX2 RNA structure. Additionally, we hypothesize that the human ortholog of MLE, DHX9, employs a similar autoregulatory mechanism. DHX9 is closely associated with HIV, autoimmune disorders, and cancers due to its involvement in replication, miRNA processing, translation, and viral infection. Therefore, DHX9 has been identified as a promising drug target. We aim to demonstrate that the interface between its double-stranded RNA binding domain and the helicase core module can serve as a suitable site to develop a specific inhibitor.

• DFG Programme: Research Grants