Birth-and-death evolution of protein-coding regions and concerted evolution of non-coding regions in the multi-component genomes of nanoviruses.
Genomes of the four plant viruses of the genus Nanovirus consist of multiple circular single-stranded DNA components, each of which encodes a single protein. Protein phylogenies supported the hypothesis that faba bean necrotic yellows virus (FBNYV) and milk vetch disease virus (MDV) are sister taxa; that subterranean clover stunt virus (SCSV) branched next; and that banana bunchy top virus (BBTV) is an outgroup to the three other species. The phylogeny of replication (Rep) proteins indicate that this small viral multi-gene family has evolved by a process of duplication and subsequent loss of Rep-encoding genome components, analogous to the "birth-and-death" process of evolution which has been described in eukaryotic multi-gene families. By contrast, repeated recombinational events between components were found to have homogenized the non-coding portions of several components encoding unrelated components. For example, as result of recent recombination a portion of the non-coding region is virtually identical among SCSV components 1, 3, 4, 5, and 7. Thus, there is a process of concerted evolution of non-coding regions of Nanovirus genome components, which raises the possibility that certain non-coding regions are subject to functional constraint.
Hughes
Austin L
AL
Department of Biological Sciences, University of South Carolina, Coker Life Sciences Building, 700 Sumter St, Columbia, SC 29208, USA. austin@biol.sc.edu
D001483:Base Sequence; D004277:DNA, Single-Stranded; D019143:Evolution, Molecular; D016679:Genome, Viral; D008969:Molecular Sequence Data; D005810:Multigene Family; D025682:Nanovirus / Q000235:genetics*; D016366:Open Reading Frames; D010802:Phylogeny; D011506:Proteins / Q000235:genetics*
D004277:DNA, Single-Stranded; D011506:Proteins