The pseudorabies virus Us2 protein, a virion tegument component, is prenylated in infected cells.
The Us2 gene is conserved among alphaherpesviruses, but its function is not known. We demonstrate here that the pseudorabies virus (PRV) Us2 protein is synthesized early after infection and localizes to cytoplasmic vesicles and to the plasma membrane, despite the lack of a recognizable signal sequence or membrane-spanning domain. Us2 protein is also packaged as part of the tegument of mature virions. The Us2 carboxy-terminal four amino acids comprise a CAAX motif, a well-characterized signal for protein prenylation. Treatment of infected cells with lovastatin, a drug that disrupts protein prenylation, changed the relative electrophoretic mobility of Us2 in sodium dodecyl sulfate-polyacrylamide gels. In addition, lovastatin treatment caused a dramatic relocalization of Us2 to cytoplasmic punctate structures associated with microtubules, which appeared to concentrate over the microtubule organizing center. When the CAAX motif was changed to GAAX and the mutant protein was synthesized from an expression plasmid, it concentrated in punctate cytoplasmic structures reminiscent of Us2 localization in infected cells treated with lovastatin. We suggest that prenylation of PRV Us2 protein is required for proper membrane association. Curiously, the Us2 protein isolated from purified virions does not appear to be prenylated. This is the first report to describe the prenylation of an alphaherpesvirus protein.
Department of Microbiology, University of Colorado Health Sciences Center, Denver, Colorado 80262, USA.
Amanda C
AC
Clase
Mathew G
MG
Lyman
T
T
del Rio
Jessica A
JA
Randall
Christine M
CM
Calton
L W
LW
Enquist
Bruce W
BW
Banfield
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D011558:Herpesvirus 1, Suid / Q000737:chemistry*; D008969:Molecular Sequence Data; D017368:Protein Prenylation; D013552:Swine; D014162:Transfection; D014759:Viral Envelope Proteins / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*; D014774:Virulence; D019065:Virus Assembly; D014779:Virus Replication
C118670:US2 protein, Varicellovirus; D014759:Viral Envelope Proteins