The N-terminal domain of Type IV-A1 CRISPR-associated DinG is vulnerable to proteolysis.
Hallmark, T., Williams, A.A., Redman, O., Guinn, B., Judd, C., Jackson, R.N.(2024) MicroPubl Biol 2024
- PubMed: 38911435 
- DOI: https://doi.org/10.17912/micropub.biology.001226
- Primary Citation of Related Structures:  
8V44 - PubMed Abstract: 
CasDinG is an ATP-dependent 5'-3' DNA helicase essential for bacterial Type IV-A1 CRISPR associated immunity. CasDinG contains an essential N-terminal domain predicted to bind DNA. To better understand the role of the N-terminal domain, we attempted to co-crystallize CasDinG with DNA substrates. We successfully crystallized CasDinG in a tightly packed, crystal conformation with previously unobserved unit cell dimensions. However, the structure lacked electron density for a bound DNA substrate and the CasDinG N-terminal domain. Additionally, the tight crystal packing disallowed space for the N-terminal domain, indicating that the N-terminal domain was proteolyzed before crystallization. Follow up experiments revealed that the N-terminal domain of CasDinG is proteolyzed after a few days at room temperature, but is protected from proteolysis at 4°C. These data provide a distinct x-ray crystal structure of CasDinG and indicate the essential N-terminal domain of CasDinG is prone to proteolysis.
Organizational Affiliation: 
Department of Chemistry and Biochemistry, Utah State University, Logan, Utah, United States.