ANP32B Is a Nuclear Target of Henipavirus M Proteins

Abstract

Membrane envelopment and budding of negative strand RNA viruses (NSVs) is mainly driven by viral matrix proteins (M). In addition, several M proteins are also known to be involved in host cell manipulation. Knowledge about the cellular targets and detailed molecular mechanisms, however, is poor for many M proteins. For instance, Nipah Virus (NiV) M protein trafficking through the nucleus is essential for virus release, but nuclear targets of NiV M remain unknown. To identify cellular interactors of henipavirus M proteins, tagged Hendra Virus (HeV) M proteins were expressed and M-containing protein complexes were isolated and analysed. Presence of acidic leucine-rich nuclear phosphoprotein 32 family member B (ANP32B) in the complex suggested that this protein represents a direct or indirect interactor of the viral matrix protein. Over-expression of ANP32B led to specific nuclear accumulation of HeV M, providing a functional link between ANP32B and M protein. ANP32B-dependent nuclear accumulation was observed after plasmid-driven expression of HeV and NiV matrix proteins and also in NiV infected cells. The latter indicated that an interaction of henipavirus M protein with ANP32B also occurs in the context of virus replication. From these data we conclude that ANP32B is a nuclear target of henipavirus M that may contribute to virus replication. Potential effects of ANP32B on HeV nuclear shuttling and host cell manipulation by HeV M affecting ANP32B functions in host cell survival and gene expression regulation are discussed.

Nipah Virus Matrix Protein Influences Fusogenicity and Is Essential for Particle Infectivity and Stability

“…Supporting the idea of a critical role in virus particle formation and budding, NiV M protein forms virus-like particles (VLPs) when expressed on its own (12,13), and it drives apical assembly and budding of NiV virions in polarized epithelial cells (14). Trafficking of NiV M is a complex process involving transit through the nucleus (15)(16)(17)(18), despite replication occurring exclusively in the cytoplasm. When NiV M protein nuclear localization or export signals are interrupted, or if the endosomal sorting complexes required for transport (ESCRT) pathway-interacting late domains are disrupted, NiV M proteins lose their ability to accumulate at the plasma membrane and no longer generate virus-like particles (12,17,19).…”

Roles of nuclear trafficking in infection by cytoplasmic negative-strand RNA viruses: paramyxoviruses and beyond

“…Alanine mutagenesis of key leucine residues in corresponding sequences in the M proteins of HeV, SeV and MuV also increased their nuclear accumulation (Pentecost et al, 2015), indicative of conservation of the NES in multiple paramyxoviruses. As HeV M export is inhibited by LMB, it appears that this NES is CRM1 dependent (Bauer et al, 2014). Equivalent mutations in NDV M and MeV M, however, did not cause nuclear accumulation (Pentecost et al, 2015), suggestive of divergence in the NESs used by these proteins.…”

Nipah virus matrix protein: expert hacker of cellular machines

“…Disruption of either of the two putative classical leucine-rich NES sequences in NiV-M increased nuclear localization of M, but only the N-terminal NES-mediated nuclear export when fused to a heterologous protein [33]. As expected for a protein bearing a leucine-rich NES, nuclear export of M is sensitive to inhibition with leptomycin B (LMB) [66], indicating transport requires chromosome region maintenance 1 (Crm1, XPO1), one of the seven karyo-pherin-β superfamily nuclear export proteins (XPO1-7) [67,68]. …”

“…Interestingly, a proteomics-based interaction study identified acidic leucine-rich nuclear phosphoprotein 32 member B (ANP32B), a Crm1 transport adaptor for mRNA [69], as a HNV matrix (HNV-M)-interacting protein [66]. Overexpression of ANP32B resulted in nuclear retention of both NiV and HeV-M, suggesting a possible role in M protein trafficking [66].…”