Essential and multifunctional mpox virus E5 helicase-primase in double and single hexamer

Area of Science:

• Virology
• Structural Biology
• Molecular Biology

Background:

• The 2022 mpox virus outbreak highlights the urgent need to understand poxviral replication.
• Mpox virus E5 helicase-primase is crucial for viral DNA replication, but its mechanism remains unclear.

Purpose of the Study:

• To elucidate the molecular mechanisms of mpox virus E5 helicase-primase activity.
• To determine the structural basis of mpox virus DNA replication.

Main Methods:

• X-ray crystallography was used to determine seven structures of mpox virus E5 in double hexamer (DH) and six in single hexamer conformations.
• Analysis of the structures identified key residues involved in double-stranded DNA (dsDNA) binding.

Main Results:

• Seven crystal structures of mpox virus E5 were solved, revealing distinct double hexamer and single hexamer conformations.
• The structures suggest a rotation mechanism for helicase activity and a coupled action for primase activity.
• Specific residues (Arg249, Lys286, Lys315, Lys317) were identified as critical for dsDNA binding.

Conclusions:

• The determined structures provide unprecedented insights into the functional mechanisms of mpox virus E5.
• Understanding these mechanisms is vital for developing targeted therapeutics against mpox and smallpox viruses.