@article{a64bf0639dfa4cf7859dc79f1374eec9,
title = "Structures of an active type III-A CRISPR effector complex",
abstract = "Clustered regularly interspaced short palindromic repeats (CRISPR) and their CRISPR-associated proteins (Cas) provide many prokaryotes with an adaptive immune system against invading genetic material. Type III CRISPR systems are unique in that they can degrade both RNA and DNA. In response to invading nucleic acids, they produce cyclic oligoadenylates that act as secondary messengers, activating cellular nucleases that aid in the immune response. Here, we present seven single-particle cryo-EM structures of the type III-A Staphylococcus epidermidis CRISPR effector complex. The structures reveal the intact S. epidermidis effector complex in an apo, ATP-bound, cognate target RNA-bound, and non-cognate target RNA-bound states and illustrate how the effector complex binds and presents crRNA. The complexes bound to target RNA capture the type III-A effector complex in a post-RNA cleavage state. The ATP-bound structures give details about how ATP binds to Cas10 to facilitate cyclic oligoadenylate production.",
keywords = "CRISPR, complex with ATP, complex with target RNA, crRNA, cryo-EM, structure, type III-A",
author = "Smith, {Eric M.} and S{\'e} Ferrell and Tokars, {Valerie L.} and Alfonso Mondrag{\'o}n",
note = "Funding Information: We thank members of the Mondrag{\'o}n laboratory for discussions and assistance. We thank Bryan Dorsey, Peter Rosenthal, and Kasia Soczek for advice. We are grateful to Asma Hatoum-Aslan for providing the Staphylococcus epidermidis strains used for this project. Research was supported by the NIH (grant no. R35-GM118108, to A.M.) and an American Cancer Society Postdoctoral Fellowship (134255-PF-20-041-01-DMC, to E.M.S.). We acknowledge assistance from the Northwestern University Structural Biology Facility and the Northwestern University Keck Biophysics Facility. Support from the R.H. Lurie Comprehensive Cancer Center of Northwestern University to the Structural Biology and Keck Biophysics Facilities is acknowledged. Some of this work was performed at the Stanford-SLAC Cryo-EM Center (S2C2) and at the National Center for CryoEM Access and Training (NCCAT) and the Simons Electron Microscopy Center located at the New York Structural Biology Center (NYSBC). We thank Hui Wei (NYSBC), Mahira Aragon (NYSBC), Lydia-Marie Joubert (SLAC), and Yan Liu (SLAC) for their support. S2C2 and NCCAT are supported by the National Institutes of Health Common Fund Transformative High-Resolution Cryo-Electron Microscopy program (U24 GM129541 and U24 GM129539, respectively) and NCCAT is supported by grants from the Simons Foundation (SF349247) and the New York State Assembly. E.M.S. purified samples, prepared EM samples, collected and processed EM data, built models, and wrote the manuscript. S.F. purified and prepared samples and performed the biochemical assays. V.L.T. helped collect data. A.M. helped with data processing and supervised the research. E.M.S. and A.M. wrote the manuscript with input from all of the authors. All of the authors edited the manuscript. The authors declare no competing interests. One or more of the authors of this paper self-identifies as an underrepresented ethnic minority in science. Funding Information: We thank members of the Mondrag{\'o}n laboratory for discussions and assistance. We thank Bryan Dorsey, Peter Rosenthal, and Kasia Soczek for advice. We are grateful to Asma Hatoum-Aslan for providing the Staphylococcus epidermidis strains used for this project. Research was supported by the NIH (grant no. R35-GM118108 , to A.M.) and an American Cancer Society Postdoctoral Fellowship ( 134255-PF-20-041-01-DMC , to E.M.S.). We acknowledge assistance from the Northwestern University Structural Biology Facility and the Northwestern University Keck Biophysics Facility. Support from the R.H. Lurie Comprehensive Cancer Center of Northwestern University to the Structural Biology and Keck Biophysics Facilities is acknowledged. Some of this work was performed at the Stanford-SLAC Cryo-EM Center (S 2 C 2 ) and at the National Center for CryoEM Access and Training (NCCAT) and the Simons Electron Microscopy Center located at the New York Structural Biology Center (NYSBC). We thank Hui Wei (NYSBC), Mahira Aragon (NYSBC), Lydia-Marie Joubert (SLAC), and Yan Liu (SLAC) for their support. S 2 C 2 and NCCAT are supported by the National Institutes of Health Common Fund Transformative High-Resolution Cryo-Electron Microscopy program ( U24 GM129541 and U24 GM129539 , respectively) and NCCAT is supported by grants from the Simons Foundation ( SF349247 ) and the New York State Assembly . Publisher Copyright: {\textcopyright} 2022 Elsevier Ltd",
year = "2022",
month = aug,
day = "4",
doi = "10.1016/j.str.2022.05.013",
language = "English (US)",
volume = "30",
pages = "1109--1128.e6",
journal = "Structure with Folding & design",
issn = "0969-2126",
publisher = "Cell Press",
number = "8",
}