6DD5

Crystal Structure of the Cas6 Domain of Marinomonas mediterranea MMB-1 Cas6-RT-Cas1 Fusion Protein

Summary for 6DD5

• Entry DOI: 10.2210/pdb6dd5/pdb
• Related PRD ID: PRD_900001
• Descriptor: MMB-1 Cas6 Fused to Maltose Binding Protein,CRISPR-associated endonuclease Cas1, alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose, GLYCEROL, ... (4 entities in total)
• Functional Keywords: crispr cas protein, endoribonuclease, hydrolase
• Biological source: Escherichia coli O157:H7; More
• Total number of polymer chains: 2
• Total formula weight: 153068.14

Authors

Stamos, J.L.,Mohr, G.,Silas, S.,Makarova, K.S.,Markham, L.M.,Yao, J.,Lucas-Elio, P.,Sanchez-Amat, A.,Fire, A.Z.,Koonin, E.V.,Lambowitz, A.M. (deposition date: 2018-05-09, release date: 2018-10-17, Last modification date: 2023-10-11)

Primary citation

Mohr, G.,Silas, S.,Stamos, J.L.,Makarova, K.S.,Markham, L.M.,Yao, J.,Lucas-Elio, P.,Sanchez-Amat, A.,Fire, A.Z.,Koonin, E.V.,Lambowitz, A.M.
A Reverse Transcriptase-Cas1 Fusion Protein Contains a Cas6 Domain Required for Both CRISPR RNA Biogenesis and RNA Spacer Acquisition.
Mol. Cell, 72:700-, 2018

PubMed Abstract: Prokaryotic CRISPR-Cas systems provide adaptive immunity by integrating portions of foreign nucleic acids (spacers) into genomic CRISPR arrays. Cas6 proteins then process CRISPR array transcripts into spacer-derived RNAs (CRISPR RNAs; crRNAs) that target Cas nucleases to matching invaders. We find that a Marinomonas mediterranea fusion protein combines three enzymatic domains (Cas6, reverse transcriptase [RT], and Cas1), which function in both crRNA biogenesis and spacer acquisition from RNA and DNA. We report a crystal structure of this divergent Cas6, identify amino acids required for Cas6 activity, show that the Cas6 domain is required for RT activity and RNA spacer acquisition, and demonstrate that CRISPR-repeat binding to Cas6 regulates RT activity. Co-evolution of putative interacting surfaces suggests a specific structural interaction between the Cas6 and RT domains, and phylogenetic analysis reveals repeated, stable association of free-standing Cas6s with CRISPR RTs in multiple microbial lineages, indicating that a functional interaction between these proteins preceded evolution of the fusion.

PubMed: 30344094
DOI: 10.1016/j.molcel.2018.09.013

Experimental method

X-RAY DIFFRACTION (2.85 Å)