ADP-ribosyltransferase that efficiently ADP-ribosylates one of the two alpha subunits of host RNA polymerase RPOA on an arginine located in the C-terminal region (PubMed:16112649, PubMed:173540). ADP-ribosylation of RPOA alpha subunit enhances the transcription of viral early genes (PubMed:11021939). Also ribosylates RPOA subunits beta, beta' and sigma 70 and performs an autoribosylation reaction (PubMed:9193638, PubMed:173540). Additional in-vitro identified targets include proteins involved in either translation or cellular metabolism such as elongation factor-Tu or GroeL (PubMed:16112649). Mono-ADP-ribosylates host MAZF which may inactivate the latter (PubMed:26395283). L-arginyl-[protein] + NAD(+) = H(+) + N(omega)-(ADP-D-ribosyl)-L-arginyl-[protein] + nicotinamide Optimum pH is 7.5. Optimum temperature is 20 degrees Celsius. About 25-50 copies per virion. This protein is injected into the bacterial cell along with the viral DNA. Belongs to the Tevenvirinae NAD(+)--arginine ADP-ribosyltransferase family.