Two types of non-homologous RNA recombination in brome mosaic virus.
Non-homologous RNA recombination is a process enabling the exchange of genetic material between various (related or unrelated) RNA-based viruses. Despite extensive investigations its molecular mechanism remains unclear. Studies on genetic recombination in brome mosaic virus (BMV) have shown that local hybridization between genomic RNAs induces frequent non-homologous crossovers. A detailed analysis of recombinant structures suggested that local complementary regions might be involved in two types of non-homologous recombination in BMV: site-specific and heteroduplex-mediated. To verify the above hypothesis and better recognize the mechanism of the phenomenon studied we have tested how the putative types of recombination are affected by a specific mutation in the BMV polymerase gene or by changes in RNA structure. The experiments undertaken revealed substantial differences between site-specific and heteroduplex-mediated recombination, indicating that they occur according to different mechanisms. The former can be classified as homology-assisted, and the latter as homology-independent. In addition to local RNA/RNA hybridization, short regions of homology are required for site-specific crossovers to occur. They are most efficiently mediated if one homologous sequence is located at the beginning of and the second just before a double-stranded region. At present it is difficult to state what is the mechanism of heteroduplex-mediated recombination. Earlier it was postulated that strong RNA/RNA interaction enforces template switching by the viral replicase. There are, however, several observations questioning this model and indicating that some other factors, which are still unknown, may influence heteroduplex-mediated crossovers.
Alejska
Magdalena
M
Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poznań, Poland.
Malinowska
Nelli
N
Urbanowicz
Anna
A
Figlerowicz
Marek
M
D001483:Base Sequence; D017795:Bromovirus / Q000235:genetics*; D017931:DNA Primers; D016679:Genome, Viral; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009154:Mutation; D012367:RNA, Viral / Q000235:genetics*; D011995:Recombination, Genetic; D020133:Reverse Transcriptase Polymerase Chain Reaction
D017931:DNA Primers; D012367:RNA, Viral