title: The U(L)3 protein of herpes simplex virus 1 is translated predominantly from the second in-frame methionine codon and is subject to at least two posttranslational modifications.
abstract: The U(L)3 open reading frame (ORF) has the coding capacity of 235 codons. The proteins reacting with the anti-U(L)3 antibody form in denaturing polyacrylamide gel bands with apparent M(r)s of 34,000, 35,000, 38,000, 40,000, 41,000, and 42,000 and designated 1 to 6, respectively. Studies on their origins revealed the following. (i) The U(L)3 proteins forming all six bands were present in lysates of cells infected with wild-type virus and treated with tunicamycin or monensin or in cells infected with the mutant lacking the gene encoding the U(S)3 protein kinase. (ii) The proteins contained in the slower-migrating bands were absent from cells infected with the mutant lacking the U(L)13 protein kinase. Bands 1 and 3, however were phosphorylated in cells infected with this mutant. (iii) Band 2 protein was absent from cells transfected with a plasmid carrying a substitution of the predicted first methionine codon of the U(L)3 ORF and superinfected with the U(L)3(-) mutant. (iv) Band 1 and 3 proteins were absent from lysates of cells transfected with a plasmid carrying a substitution of the second (M12) methionine codon of the U(L)3 ORF and superinfected with the U(L)3(-) mutant. (v) Cells superinfected with mutants lacking both methionine codons did not accumulate any of the proteins contained in the six bands. (vi) In vitro transcription-translation studies indicated that the translation of band 1 protein was initiated from the second (M12) methionine codon and that band 3 protein represented a U(L)13-independent, posttranslationally processed form of these proteins. The results indicate that the U(L)3 protein of herpes simplex virus 1 is translated predominantly from the second in-frame methionine codon and is subject to at least two posttranslational modifications.
authors.affiliation: The Marjorie B. Kovler Viral Oncology Laboratories, The University of Chicago, Chicago, Illinois 60637, USA.
authors.forename: N S
authors.initials: NS
authors.lastname: Markovitz
authors.forename: F
authors.initials: F
authors.lastname: Filatov
authors.forename: B
authors.initials: B
authors.lastname: Roizman
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002522:Chlorocebus aethiops; D003062:Codon / Q000235:genetics; D018259:Herpesvirus 1, Human / Q000502:physiology*; D006801:Humans; D008715:Methionine / Q000235:genetics; D008969:Molecular Sequence Data; D016366:Open Reading Frames / Q000235:genetics; D014176:Protein Biosynthesis; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D014709:Vero Cells; D014764:Viral Proteins / Q000235:genetics* / Q000378:metabolism; D014779:Virus Replication / Q000235:genetics
chemical_list: D003062:Codon; D020033:Protein Isoforms; C121640:UL3 protein, Human herpesvirus 1; D014764:Viral Proteins; D008715:Methionine