The CRISPR system is an adaptive RNA-based microbial immune system against invasive genetic elements. CasB is an essential protein component in Type I-E Cascade. Here, we characterize CasB proteins from three different organisms as non-specific nucleic acid binding proteins. The Thermobifida fusca CasB crystal structure reveals conserved positive surface charges, which we show are important for its nucleic acid binding function. EM docking reveals that CasB dimerization aligns individual nucleic acid binding surfaces into a curved, elongated binding surface inside Type I-E Cascade, consistent with the putative functions of CasB in ds-DNA recruitment and crRNA-DNA duplex formation steps. Structured summary of protein interactions: TthCasB and TthCasB bind by x-ray crystallography (View interaction) TfuCasB1 and TfuCasB1 bind by molecular sieving (View Interaction: 1, 2) © 2012 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.
Nam, K. H., Huang, Q., & Ke, A. (2012). Nucleic acid binding surface and dimer interface revealed by CRISPR-associated CasB protein structures. FEBS Letters, 586(22), 3956–3961. https://doi.org/10.1016/j.febslet.2012.09.041