The herpes simplex virus Us11 open reading frame encodes a sequence-specific RNA-binding protein.

Herpes simplex virus 1- and 2 (HSV-1 and HSV-2)-infected cell extracts but not uninfected cell extracts contain an RNA-binding activity for an in vitro-transcribed sequence from the domains of the HSV-1 US11 and alpha 47 genes. The transcript of this sequence has not been detected in infected cells. The binding is sequence and secondary structure specific and protects approximately 95 nucleotides from RNase digestion. Analyses of HSV-1 x HSV-2 recombinants and HSV-1 deletion mutants mapped the function necessary for activity to the US11 or alpha 47 open reading frame. The alpha 47 gene was excluded, since the RNA-binding activity is a late (gamma 2) function dependent on viral DNA synthesis for its expression. The US11 function is the only viral function required, since translation in rabbit reticulocyte lysate of an in vitro-synthesized US11 mRNA resulted in the appearance of the RNA-binding activity. The product of the US11 open reading frame is associated with the RNA probe-protein complex inasmuch as insertion of a sequence encoding in frame 15 additional amino acids at the C terminus of the US11 protein caused a corresponding decrease in the electrophoretic mobility of the binding complex.