STRUCTURE AND FUNCTION IN THE HERPES-SIMPLEX-VIRUS-1 RNA-BINDING PROTEIN U(S)11 - MAPPING OF THE DOMAIN REQUIRED FOR RIBOSOMAL AND NUCLEOLAR ASSOCIATION AND RNA-BINDING IN-VITRO

The herpes simplex virus 1 U(S)11 protein is an RNA-binding regulatory protein that specifically and stably associates vith 60S ribosomal su bunits and nucleoli and is incorporated into virions, We report that U (S)11/beta-galactosidase fusion protein expressed in bacteria bound to rRNA from the 60S subunit and not the 30S subunit, This binding refle cts the specificity of ribosomal subunit association, Analyses of dele tion mutants of the U(S)11 gene showed that specific RNA binding activ ity, nucleolar localization, and association with 60S ribosomal subuni ts were found to map to the amino acid sequences of the carboxyl termi nus of U(S)11 protein, suggesting that these activities all reflect sp ecific binding of U(S)11 to large subunit rRNA. The carboxyl-terminal half of the protein consists of a regular tripeptide repeat of the seq uence RXP and constitutes a completely novel RNA-binding domain. All o f the mutant U(S)11 proteins could be incorporated into virus particle s, suggesting that the signal for virion incorporation either is at th e amino-terminal four amino acids or is redundant in the protein.