Project C05

Principal Investigators

Dr. Maria Rosenthal & Prof. Dr. Maya Topf


CSSB – Center for Structural Systems Biology
Bernhard Nocht Institute for Tropical Medicine &
Leibniz Institut of Virology/University Medical Center Hamburg- Eppendorf

C5

PhD candidate

Annika Rammelt


C5

Project Summary

The mechanism of Z-based RNA synthesis inhibition in Lassa virus as an antiviral strategy

Lassa virus is the causative agent of Lassa fever and is listed on the WHO R&D blueprint, which emphasizes the urgent need for medical countermeasures [1]. A key event in the viral life cycle is RNA replication, an orchestrated process requiring protein-protein and protein-RNA interaction. The viral matrix protein (Z) is known to inhibit the polymerase function of the viral L protein, suggesting a crucial role in the transition from genome replication to ribonucleoparticle recruitment and budding [2,3]. Structures of L-Z complexes have recently demonstrated that Z binds to the rim of the L protein core [4], which suggests steric hindrance of RNA elongation [5]. However, the exact mechanism of RNA synthesis inhibition remains unexplored as the L-Z complex structures were solved in the absence of viral RNA.

Aiming to address this question, the project focusses on structural characterization of the L-Z interaction in the presence of viral RNA and during RNA synthesis using single particle cryogenic electron microscopy (cryo-EM). Biochemical and biophysical in vitro assays as well as cell-based assays are used for validation.Furthermore, we hypothesize that the Z-mediated inhibition of L presents a promising opportunity for rational drug design. Hence, we aim to clarify the mechanism of Z-based polymerase inhibition for Lassa virus and evaluate its potential as an antiviral strategy supported by in silico peptide design and docking experiments.

Structural comparison of the L protein during RNA synthesis (PDB:7OJN) and L-Z complex (PDB:7CKL) reveals a steric clash, assumed to be the mechanism of action for Z-based polymerase inhibition. We aim to clarify this mechanism and its consequences for viral RNA binding.

References:

  1. Friedrich MJ. WHO’s Blueprint List of Priority Diseases. JAMA. 2018 May 15;319(19):1973. doi: 10.1001/jama.2018.5712
  2. Kranzusch PJ, Whelan SP. Arenavirus Z protein controls viral RNA synthesis by locking a polymerase-promoter complex. Proc Natl Acad Sci U S A. 2011 Dec 6;108(49):19743-8. doi: 10.1073/pnas.1112742108.
  3. Vogel D, Rosenthal M, Gogrefe N, et al. Biochemical characterization of the Lassa virus L protein. J Biol Chem. 2019 May 17;294(20):8088-8100. doi: 10.1074/jbc.RA118.006973
  4. Xu X, Peng R, Peng Q, et al. Cryo-EM structures of Lassa and Machupo virus polymerases complexed with cognate regulatory Z proteins identify targets for antivirals. Nat Microbiol. 2021 Jul;6(7):921-931. doi: 10.1038/s41564-021-00916-w.
  5. Kouba T, Vogel D, Thorkelsson SR, et al. Conformational changes in Lassa virus L protein associated with promoter binding and RNA synthesis activity. Nat Commun. 2021 Dec 2;12(1):7018. doi: 10.1038/s41467-021-27305-5.