title: Phosphorothioate analogues of (2'-5')(A)4: agonist and antagonist activities in intact cells.
abstract: Metabolically stable phosphorothioate tetramer analogues of (2'-5')(A)n with Rp and/or Sp chirality in the 2'-5'-phosphodiester linkages constitute a new class of antiviral agents since they mimic the effects of interferons. Three of the diastereomeric 5'-monophosphates (i.e., pRpRpRp, pSpRpRp, and pRpSpSp) bind to and activate RNase L from extracts of HeLa cells. However, the pSpSpSp (2'-5')-(A)4-phosphorothioate is unique in that it binds to, but cannot activate, RNase L to cleave rRNA. When microinjected into the cytoplasm of HeLa cells followed by virus infection, the pRpRpRp, pSpRpRp, and pRpSpSp (2'-5')(A)4-phosphorothioates demonstrate antiviral activity, as does (2'-5')(A)4ox-red, an active (2'-5')(A)n analogue. When microinjected simultaneously with (2'-5')(A)nox-red, an active the pSpSpSp (2'-5')(A)4-phosphorothioate inhibits activation of RNase L in HeLa cells, thereby blocking direct protection of vesicular stomatitis virus. The agonist and antagonist properties of pRpRpRp and pSpSpSp, respectively, are transient probably as a consequence of the hydrolysis of the 5'-monophosphate and formation of the less active (2'-5')(A)4-phosphorothioate cores. The possible use of these (2'-5')(A)4-phosphorothioates as tools for dissecting the biological significance of the (2'-5')(A)n system or in antiviral chemotherapy is discussed.
authors.affiliation: Laboratoire de Biochimie des Proteines, UA CNRS 1191, Universitè de Montpellier II, France.
authors.forename: G
authors.initials: G
authors.lastname: Charachon
authors.forename: R W
authors.initials: RW
authors.lastname: Sobol
authors.forename: C
authors.initials: C
authors.lastname: Bisbal
authors.forename: T
authors.initials: T
authors.lastname: Salehzada
authors.forename: M
authors.initials: M
authors.lastname: Silhol
authors.forename: R
authors.initials: R
authors.lastname: Charubala
authors.forename: W
authors.initials: W
authors.lastname: Pfleiderer
authors.forename: B
authors.initials: B
authors.lastname: Lebleu
authors.forename: R J
authors.initials: RJ
authors.lastname: Suhadolnik
mesh_terms: D000998:Antiviral Agents / Q000494:pharmacology*; D055598:Chemical Phenomena; D002621:Chemistry; D004722:Endoribonucleases / Q000037:antagonists & inhibitors*; D004789:Enzyme Activation; D006367:HeLa Cells; D006801:Humans; D007700:Kinetics; D009691:Nucleic Acid Denaturation; D009946:Organothiophosphorus Compounds / Q000494:pharmacology*; D010766:Phosphorylation; D011116:Polynucleotide 5'-Hydroxyl-Kinase / Q000378:metabolism; D012335:RNA, Ribosomal / Q000187:drug effects / Q000302:isolation & purification; D014721:Vesicular stomatitis Indiana virus / Q000187:drug effects* / Q000201:enzymology / Q000254:growth & development; D014779:Virus Replication / Q000187:drug effects*
chemical_list: D000998:Antiviral Agents; D009946:Organothiophosphorus Compounds; D012335:RNA, Ribosomal; D011116:Polynucleotide 5'-Hydroxyl-Kinase; D004722:Endoribonucleases; C031956:2-5A-dependent ribonuclease