Schematic representation of plasmids and Pl.LSU/2 intron domain IV used.

<p>(<i>A</i>) Gray rectangles: Predicted protein domains shared by other group II intron ORFs; E2 and E3: exons flanking the Pl.LSU/2 group II intron <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0058263#pone.0058263-Fontaine2" target="_blank">[56]</a>; bold line: Pl.LSU/2 group II intron; broken line: vector sequences; PT7: Specific promoter of the T7 bacteriophage RNA polymerase; TT7: T7 bacteriophage RNA polymerase transcription terminator; 6xHis: histidine tag; V5: V5 epitope; hatched rectangles: 50 last nt of E2 and 71 first nt of E3; diamond: position in which the RT catalytic motif YADD is mutated in YAAA on negative control plasmids (p151-E+I+IEPmtDD- and p151-IEPmtDD-). (<i>B</i>) Predicted RNA secondary structure of Pl.LSU/2 intron domain IV (DIV). Start and Stop codons of the IEP ORF are indicated. DIVa: section conserved in the intron-DIVa form (deletion from 244 to 1772 nt of DIV). DIVab: section conserved in the intron-DIVab form (deletion from 369 to 1446 nt of DIV). ΔDIV : section conserved in the intron-ΔDIV form (section highlighted in gray); the section from 8 to 1818 nt of DIV is replaced by the sequence CCTAGGATCT<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0058263#pone.0058263-Costa1" target="_blank">[54]</a>. The detailed putative secondary structure is available in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0058263#pone.0058263.s002" target="_blank">Fig. S2</a>.