Figure 4.

Alignment of the closest available cyanobacterial one-piece and two-piece tmRNA sequences. Plus signs mark base identities between one-piece Synechococcus PCC6301 and two-piece Synechococcus WH8102 sequences. Conservation summaries for one-piece (Fig. 3) and two-piece (4) tmRNAs are shown. Indications are as in Figure 3. The alignment of the ‘Ex-PK1 Block’ maximizes base identity matches but shifts comparable structural elements. Alignment is instead forced for pairings P6–P8 and may not represent true sequence homology.