Vaccinia virus G4L gene encodes a second glutaredoxin.

Vaccinia virus (VV) was previously shown to encode a functional glutaredoxin, the product of the o2l gene, which is synthesized late in infection, after the onset of DNA replication. Here we report that an open reading frame in the VV genome designated as g4l encodes a protein that has sequence similarity to glutaredoxins and possesses thioltransferase and dehydroascorbate reductase activities. G4L protein in infected cells can be detected as early as 4 hr after infection and is constitutively expressed up to 24 hr postinfection. A protein homologous to G4L and retaining the predicted glutaredoxin active center is encoded by the recently sequenced Molluscum Contagiosum virus (MCV), whereas O2L protein is not conserved, suggesting that the glutaredoxin activity of G4L may be involved in replication of all poxviruses.