A STUDY OF THE DIMERIZATION OF ROUS-SARCOMA VIRUS-RNA IN-VITRO AND IN-VIVO

The Rous sarcoma virus dimer linkage site (DLS) has been located by el ectron microscopy at position 511 +/- 28 nucleotides. We have studied the dimerization of RNAs encompassing the first 634 nucleotides of Rou s sarcoma virus and conclude that there are at least two dimerization signals. One is located between nucleotides 531 and 634 and may involv e Watson-Crick pairing of an imperfect inverted repeat. The other sign al is located between nucleotides 496 and 530. A tetraguanine sequence at nucleotides 523-526 is required for dimerization of this domain. T he guanines are not involved in an identifiable Watson-Crick interacti on or in guanine tetrad formation. Either dimerization domain can init iate the dimerization of RNA 1-634. It is possible that these domains are two parts of a single dimerization signal. Interstrand RNA contact s within the virion are not limited to the DLS but occur along the len gth of the genome. Nascent virions contain monomeric RNA which slowly associates to form an RNA dimer, The limiting step in dimerization is not proteolytic cleavage of the gag precursor because only the mature capsid protein p27 can be detected in these nascent virions. (C) 1995 Academic Press, Inc.