Patterson, AngelaWhite, AidanWaymire, ElizabethFleck, SophieGolden, SarahWilkinson, Royce A.Wiedenheft, BlakeBothner, Brian2023-01-252023-01-252022-10Angela Patterson, Aidan White, Elizabeth Waymire, Sophie Fleck, Sarah Golden, Royce A Wilkinson, Blake Wiedenheft, Brian Bothner, Anti-CRISPR proteins function through thermodynamic tuning and allosteric regulation of CRISPR RNA-guided surveillance complex, Nucleic Acids Research, Volume 50, Issue 19, 28 October 2022, Pages 11243–11254, https://doi.org/10.1093/nar/gkac8410305-1048https://scholarworks.montana.edu/handle/1/17631CRISPR RNA-guided detection and degradation of foreign DNA is a dynamic process. Viruses can interfere with this cellular defense by expressing small proteins called anti-CRISPRs. While structural models of anti-CRISPRs bound to their target complex provide static snapshots that inform mechanism, the dynamics and thermodynamics of these interactions are often overlooked. Here, we use hydrogen deuterium exchange-mass spectrometry (HDX-MS) and differential scanning fluorimetry (DSF) experiments to determine how anti-CRISPR binding impacts the conformational landscape of the type IF CRISPR RNA guided surveillance complex (Csy) upon binding of two different anti-CRISPR proteins (AcrIF9 and AcrIF2). The results demonstrate that AcrIF2 binding relies on enthalpic stabilization, whereas AcrIF9 uses an entropy driven reaction to bind the CRISPR RNA-guided surveillance complex. Collectively, this work reveals the thermodynamic basis and mechanistic versatility of anti-CRISPR-mediated immune suppression. More broadly, this work presents a striking example of how allosteric effectors are employed to regulate nucleoprotein complexes.en-UScc-byhttps://creativecommons.org/licenses/by/4.0/anti-crispranti-crispr proteinsthermodynamic tuningallosteric regulationCRISPR RNAArticle