Fig. 3.—

The CRISPR/Cas system of Bacteroides vulgatus mpk. (A) The Cas system is a complete type I-C/DVULG system as postulated in Bacillus halodurans C-125. The Cas2 annotation was manually added, as it was missed by the automated annotation pipelines. The prerequisite parts of the CRISPR/Cas type I-C system are shown in the operon: The helicase Cas3, Cas5d which is involved in interacting with pre-crRNA, Csd1 family protein, Csd2/Csh2 familiy protein, Cas4 belonging to the family of RecB exonuclases, and Cas1. The operon is followed downstream by the CRISPR region, and two mobile element proteins.(B) The CRISPR repeat secondary structure was predicted from the repeat consensus RNA sequence obtained from the CRISPR region. It shows the conserved hairpin region which is necessary for recognition of the pre-crRNA by Cas5d to enable cleaving to obtain functional crRNA. Red bold letters indicate the nucleotide changes compared with Bacillus halodurans.