Fig. 1.

Organization of the expression plasmid and two archival linear plasmids in B. hermsii. The lengths of genes and elements are relative and not to absolute scale. There is a single expression site on one plasmid and silent variants on the same and other plasmids. The direction and extent of transcription of the duplicate gene at the expression site is indicated by the arrow. The colors of genes indicate the family or subfamily of vsp and vlp genes. Most variant genes are arrayed on the same strand in a given plasmid fragment, but some are oppositely oriented, as indicated by inverted text. The UHS element at the expression site comprises 61 nt around the start codon of the variant gene. Silent genes vary in the extent to which their UHS regions are identical to the expression-site UHS, represented here by the relative length of the UHS block. There is a 214-nt noncoding DHS element downstream from the expression site and adjacent to the plasmid telomere and at various locations on the plasmids.