Multifunctional protein that acts as a viral transcriptional activator. Promotes read-through of an RNA hairpin in the NP open reading frame to enhance viral transcription. Mechanistically, nonphosphorylated VP30 hexamers form a ternary complex with the viral leader RNA. Clamps the RNA template and the complex VP35-polymerase L together, thereby increasing the polymerase affinity for the RNA template to increase transcription initiation despite the presence of RNA secondary structures. Assists also stop-start transcription at gene junctions to promote transcription of downstream genes. Interaction with NP plays a critical role in transcription initiation by recognizing the RNA stem loop (By similarity). Interaction with host RBBP6 interferes with NP-VP30 interaction and inhibits viral RNA synthesis (PubMed:30550789). Also acts as a suppressor of RNA silencing by interacting with host DICER1 and TARBP2/TRBP (PubMed:21228243). Homohexamer; hexamerization is essential for RNA binding. Interacts with the nucleoprotein/NP; this interaction plays both essential and inhibitory roles in viral RNA synthesis. Interacts with VP35. Interacts with host STAU1 (By similarity). Interacts (via C-terminus) with host ubiquitin ligase RBBP6 isoform 1 (PubMed:30550789). Interacts with host DICER1; this interaction prevents TARBP2/TRBP binding to DICER1 and thus allows the virus to counteract host RNA silencing (PubMed:21228243). Interacts with host TARBP2/TRBP; this interaction, which occurs only in the presence of siRNA, prevents TARBP2 binding to DICER1 and thus allows the virus to counteract host RNA silencing (PubMed:21228243). Present in viral inclusion bodies due to its interaction with NP. Phosphorylated by host. Phosphorylation negatively regulates the transcription activation. Phosphorylation and dephosphorylation take place in viral inclusion bodies and are largely influenced by the presence of NP. Dephosphorylated by host PPP2R5C; this dephosphorylation enhances viral transcription and is mediated by NP. Belongs to the filoviridae transcriptional activator VP30 family.