ABSTRACT

Minus-strand RNA synthesis, the first step in the replication of plus-strand RNA viruses, is subject to multiple levels of regulation. In plant-infecting viruses, tRNA-like structures, poly(A) sequences, or one and more stem-loop structures direct minus-strand RNA synthesis. These cis-acting sequences must perform several functions for successful viral replication, which include recruiting the replication machinery, presenting an accessible initiation sequence to the viral replicase, and regulating appropriate levels of RNA synthesis. This review will summarize the structural, functional and phylogenetic analyses of the cis-acting sequences involved in minus-strand RNA synthesis, with emphasis on the much-studied brome mosaic virus.