THE HERPES-SIMPLEX VIRUS TYPE-1 UL6 PROTEIN IS ESSENTIAL FOR CLEAVAGEAND PACKAGING BUT NOT FOR GENOMIC INVERSION

The HSV-1 genome is composed of two unique regions (U-L and U-S) flank ed by inverted repeats. During the course of DNA replication the two u nique regions U, and U, invert relative to one another. in this report we present evidence that cleavage is not necessary for genomic invers ion to occur. We isolated and characterized a UL6::lacZ insertion muta nt (hr74) that produces wild-type levels of replicating viral DNA but rails to cleave and package DNA. We demonstrate that this virus is sti ll able to undergo genomic inversion. Furthermore we confirm that repl icating DNA from cells infected with wild-type virus contains specific U-L termini but not U-S termini, whereas cells infected with the muta nt hr74 do not contain either U-S or U-L termini. This demonstrates th at the specific U-L ends found in replicating DNA are the result of th e cleavage/packaging process. (C) 1996 Academic Press, Inc.