6KBD

fused To-MtbCsm1 with 2dATP

Summary for 6KBD

• Entry DOI: 10.2210/pdb6kbd/pdb
• Descriptor: CRISPR system single-strand-specific deoxyribonuclease Cas10/Csm1 (subtype III-A),CRISPR system single-strand-specific deoxyribonuclease Cas10/Csm1 (subtype III-A), 2'-DEOXYADENOSINE 5'-TRIPHOSPHATE, MAGNESIUM ION (3 entities in total)
• Functional Keywords: csm1, polymersase, dna binding protein
• Biological source: Thermococcus onnurineus NA1; More
• Total number of polymer chains: 1
• Total formula weight: 90272.65

Authors

Li, T.,Huo, Y.,Jiang, T. (deposition date: 2019-06-24, release date: 2020-06-24, Last modification date: 2024-11-13)

Primary citation

Zhang, S.,Li, T.,Huo, Y.,Yang, J.,Fleming, J.,Shi, M.,Wang, Y.,Wei, W.,Gu, S.,Bi, L.,Jiang, T.,Zhang, H.
Mycobacterium tuberculosis CRISPR/Cas system Csm1 holds clues to the evolutionary relationship between DNA polymerase and cyclase activity.
Int.J.Biol.Macromol., 170:140-149, 2020

PubMed Abstract: Prokaryotic CRISPR/Cas systems confer immunity against invading nucleic acids through effector complexes. Csm1, the signature protein of Type III effector complexes, catalyses cyclic oligoadenylate synthesis when in the effector complex, but not when alone, activating the Csm6 nuclease and switching on the antiviral response. Here, we provide biochemical evidence that M. tuberculosis Csm1 (MtbCsm1) has ion-dependent polymerase activity when independent of the effector complex. Structural studies provide supporting evidence that the catalytic core of the MtbCsm1 palm2 domain is almost identical to that of classical DNA polymerase Pol IV, and that the palm1 and B domains function as the other structural elements required (thumb and fingers) for DNA polymerase activity. MtbCsm1 polymerase activity is relatively weak in vitro and its functional relevance in vivo is unknown. Our structural and mutagenesis data suggest that residue K692 in the palm2 domain has been significant in the evolution of Csm1 from a polymerase to a cyclase, and support the notion that the cyclase activity of Csm1 requires the presence of other elements provided by the CRISPR/Cas effector complex. This structural rationale for Csm1 polymerase (alone) and cyclase (within the effector complex) activity should benefit future functional investigations and engineering.

PubMed: 33352158
DOI: 10.1016/j.ijbiomac.2020.12.014

Experimental method

X-RAY DIFFRACTION (3 Å)