5YEU

Structural and mechanistic analyses reveal a unique Cas4-like protein in the mimivirus virophage resistance element system

Summary for 5YEU

• Entry DOI: 10.2210/pdb5yeu/pdb
• Descriptor: Uncharacterized protein R354, MAGNESIUM ION (3 entities in total)
• Functional Keywords: mimivire, cas4-like, nuclease, ribosomal protein, nuclear protein
• Biological source: Acanthamoeba polyphaga mimivirus (APMV)
• Total number of polymer chains: 2
• Total formula weight: 92081.21

Authors

Dou, C.,Yu, M.J.,Gu, Y.J.,Cheng, W. (deposition date: 2017-09-19, release date: 2018-07-25, Last modification date: 2024-03-27)

Primary citation

Dou, C.,Yu, M.,Gu, Y.,Wang, J.,Yin, K.,Nie, C.,Zhu, X.,Qi, S.,Wei, Y.,Cheng, W.
Structural and Mechanistic Analyses Reveal a Unique Cas4-like Protein in the Mimivirus Virophage Resistance Element System.
Iscience, 3:1-10, 2018

PubMed Abstract: A clustered regularly interspaced short palindromic repeats (CRISPR)-like "mimivirus virophage resistance element" (MIMIVIRE) system, which contains specific cascade genes and a CRISPR array against virophages, was reported in mimiviruses. An essential component of the MIMIVIRE system is R354, encoding a nuclease and a likely functional homolog of Cas4. Here we show that R354 is a dual nuclease with both exonuclease and endonuclease activities. Structural analysis revealed that the catalytic core domain of R354 is similar to those of Cas4 and ? exonuclease despite their low sequence identity. R354 forms a homodimer that is important for its exonuclease but not endonuclease activity. Structural comparisons between the active and semi-active states of R354 demonstrated that an activation loop adjacent to the catalytic site is critical for enzymatic activity. Overall, the results suggest that R354 belongs to a novel MIMIVIRE system involved in innate virus immunity and provides a template for the identification of new CRISPR systems in other species.

PubMed: 30428313
DOI: 10.1016/j.isci.2018.04.001

Experimental method

X-RAY DIFFRACTION (3.001 Å)