The UL37 open reading frame of the herpes simplex virus type 1 (HSV-1)
DNA genome is located between map units 0.527 and 0.552. We have identified and characterized the UL37
protein product in HSV-1-infected cells. The presence of the UL37
protein was detected by using a polyclonal rabbit antiserum directed against an in vitro-translated product derived from an in vitro-transcribed UL37
mRNA. The UL37 open reading frame encodes for a
protein with an apparent molecular mass of 120 kDa in HSV-1-infected cells; the
protein's mass was assigned on the basis of its migration in
sodium dodecyl sulfate-
polyacrylamide gels. The UL37
protein is not present at detectable levels in purified HSV-1 virions, suggesting that it is not a structural
protein. Analysis of time course experiments and experiments using
DNA synthesis inhibitors demonstrated that the UL37
protein is expressed prior to the onset of
viral DNA synthesis, reaching maximum levels late in
infection, classifying it as a gamma 1 gene. Elution of HSV-1-infected cell
proteins from
single-stranded DNA agarose columns by using a linear KCl gradient demonstrated that the UL37
protein elutes from this matrix at a
salt concentration similar to that observed for ICP8, the major HSV-1
DNA-binding protein. In addition, computer-assisted analysis revealed a potential
ATP-binding domain in the predicted UL37 amino acid sequence. On the basis of the kinetics of appearance and
DNA-binding properties, we hypothesize that UL37 represents a newly recognized HSV-1
DNA-binding protein that may be involved in late events in viral replication.