Differential regulation of octamer-containing cellular genes by the herpes simplex virus virion protein Vmw65 is mediated by sequence differences in the octamer element.

The gene encoding the U3 SnRNA is transcriptionally induced early in infection with herpes simplex virus (HSV). This effect is due to the action of the HSV virion protein Vmw65 and is dependent upon the octamer motif in the U3 promoter. In contrast the U1 SnRNA gene which also contains an octamer is not activated by Vmw65 in infections or transfections. We show that this is due to sequence differences between the octamers in the U1 and U3 genes. Thus the U3 octamer can confer responsiveness to Vmw65 to truncated U1 or U3 promoters whereas the U1 octamer cannot. The use of Vmw65 as a tool to analyse the role of the octamer sequence in mediating a variety of expression patterns in different genes is discussed.