A Comprehensive Curation Shows the Dynamic Evolutionary Patterns of Prokaryotic CRISPRs

Figure 2

Detection of new DRs and spacers. (a) A CRISPR in Oscillatoria acuminata PCC 6304 has a long spacer with a truncated DR inside. The long spacer is in red and the truncated DR is in shade. DRs and spacers are represented in the left and right columns, respectively. (b) A CRISPR with DRs inserted by transposons. The newly annotated spacer regions are in red, and the new DRs are in shade. The last number in the CRISPR name is the DR copy number. (c) A CRISPR with undetected DRs inside. The two neighboring CRISPRs have almost identical DRs and one undetected DR in between. The undetected DR may be a full copy. The added region is highlighted in bold. The regions of new DRs matching the existing DRs are in shade. The regions of new spacers matching the spacers in other genomes are in shade. The last number in the CRISPR name is the DR copy number. (d) A CRISPR is broken into two at the beginning of a circular chromosome of Thermococcus litoralis DSM 5473. One more spacer is proposed to combine the two CRISPRs into one longer CRISPR. The added region (spacer) is highlighted in red.

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