ADP-ribosyltransferase that regulates transcription by ADP-ribosylation of host ribosomal protein S1 (PubMed:10634320). Additional identified targets include proteins involved in either translation or cellular metabolism such as elongation factor-Tu or trigger factor (PubMed:16112649). L-arginyl-[protein] + NAD(+) = H(+) + N(omega)-(ADP-D-ribosyl)-L-arginyl-[protein] + nicotinamide This protein is injected from the virion into the bacterial cell. Belongs to the Tevenvirinae NAD--protein ADP-ribosyltransferase modA family.