| Helicases play critical roles in a wide range of cellular processes including DNA replication,ribosome synthesis,RNA splicing,etc.Posttranslational modifications(PTMs)of helicases have essential impacts on regulating the localization,functions and stability of helicases.Here,we identified a previously undiscovered PTM-methionine oxidation in various helicases including DNA helicases(ORF44 of Kaposi’s sarcoma–associated herpesvirus and cellular MCM7)and RNA helicase of RIG-I.Interestingly,cellular viperin,a major antiviral interferon-stimulated gene(ISG)whose functions remain largely unexplored besides host defense,catalyzes the methionine oxidation of these helicases.Furthermore,studies with loss-of-function mutations of helicases and a pharmacological inhibitor indicate that methionine oxidation potently stabilizes expression and enhances functions of these helicases that are pivotal to an array of cellular processes such as DNA replication as well as immune activation.Taken together,our study verifies a vital role of viperin in catalyzing the methionine oxidation of DNA and RNA helicases,which participate in a variety of elementary cellular processes. |
