The small nonstructural protein NP1 of human bocavirus 1 directly interacts with Ku70 and RPA70 and facilitates viral DNA replication

• DOI: 10.1371/journal.ppat.1010578
• Publication Date: 2022-06-02T17:45:39Z
• Authors: Kang Ning; Zekun Wang; Fang Cheng; Ziying Yan; Jianming Qiu
• Keywords: DNA Replication; 0303 health sciences; QH301-705.5; Genome, Viral; RC581-607; Virus Replication; 3. Good health; Parvoviridae Infections; 03 medical and health sciences; Child, Preschool; Human bocavirus; DNA, Viral; Humans; Immunologic diseases. Allergy; Biology (General); Child; Research Article

Human bocavirus 1 (HBoV1), a member of the genusBocaparvovirusof the familyParvoviridae, causes acute respiratory tract infections in young children. Well-differentiated pseudostratified human airway epithelium cultured at an air-liquid interface (HAE-ALI) is an idealin vitroculture model to study HBoV1 infection. Unique to other parvoviruses, bocaparvoviruses express a small nonstructured protein NP1 of ~25 kDa from an open reading frame (ORF) in the center of the viral genome. NP1 plays an important role in viral DNA replication and pre-mRNA processing. In this study, we performed an affinity purification assay to identify HBoV1 NP1-inteacting proteins. We identified that Ku70 and RPA70 directly interact with the NP1 at a high binding affinity, characterized with an equilibrium dissociation constant (KD) of 95 nM and 122 nM, respectively. Furthermore, we mapped the key NP1-interacting domains of Ku70 at aa266-439 and of RPA70 at aa181-422. Following a dominant negative strategy, we revealed that the interactions of Ku70 and RPA70 with NP1 play a significant role in HBoV1 DNA replication not only in anin vitroviral DNA replication assay but also in HBoV1-infected HAE-ALI cultures. Collectively, our study revealed a novel mechanism by which HBoV1 NP1 enhances viral DNA replication through its direct interactions with Ku70 and RPA70.