Molecular basis of CD-NTase nucleotide selection in CBASS anti-phage defense

Anonymous — Tue, 01 Jun 2021 06:00:00 +0000

Molecular basis of CD-NTase nucleotide selection in CBASS anti-phage defense Anonymous (not verified) Tue, 06/01/2021 - 00:00

Govande AA , Duncan-Lowey B , Eaglesham JB , ➤Whiteley AT , Kranzusch PJ

Cell Rep. 2021 Jun 1;35(9):109206. doi: 10.1016/j.celrep.2021.109206.

Abstract

cGAS/DncV-like nucleotidyltransferase (CD-NTase) enzymes are signaling proteins that initiate antiviral immunity in animal cells and cyclic-oligonucleotide-based anti-phage signaling system (CBASS) phage defense in bacteria. Upon phage recognition, bacterial CD-NTases catalyze synthesis of cyclic-oligonucleotide signals, which activate downstream effectors and execute cell death. How CD-NTases control nucleotide selection to specifically induce defense remains poorly defined. Here, we combine structural and nucleotide-analog interference-mapping approaches to identify molecular rules controlling CD-NTase specificity. Structures of the cyclic trinucleotide synthase Enterobacter cloacae CdnD reveal coordinating nucleotide interactions and a possible role for inverted nucleobase positioning during product synthesis. We demonstrate that correct nucleotide selection in the CD-NTase donor pocket results in the formation of a thermostable-protein-nucleotide complex, and we extend our analysis to establish specific patterns governing selectivity for each of the major bacterial CD-NTase clades A-H. Our results explain CD-NTase specificity and enable predictions of nucleotide second-messenger signals within diverse antiviral systems.

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CBASS Immunity Uses CARF-Related Effectors to Sense 3'-5'- and 2'-5'-Linked Cyclic Oligonucleotide Signals and Protect Bacteria from Phage Infection

Anonymous — Thu, 09 Jul 2020 15:00:00 +0000

CBASS Immunity Uses CARF-Related Effectors to Sense 3'-5'- and 2'-5'-Linked Cyclic Oligonucleotide Signals and Protect Bacteria from Phage Infection Anonymous (not verified) Thu, 07/09/2020 - 09:00

Lowey B , ➤Whiteley AT , Keszei AFA , Morehouse BR , Mathews IT , Antine SP , Cabrera VJ , Kashin D , Niemann P , Jain M , Schwede F , Mekalanos JJ , Shao S , Lee ASY , Kranzusch PJ

Cell. 2020 Jul 9;182(1):38-49.e17. doi: 10.1016/j.cell.2020.05.019. Epub 2020 Jun 15.

Abstract

cGAS/DncV-like nucleotidyltransferase (CD-NTase) enzymes are immune sensors that synthesize nucleotide second messengers and initiate antiviral responses in bacterial and animal cells. Here, we discover Enterobacter cloacae CD-NTase-associated protein 4 (Cap4) as a founding member of a diverse family of >2,000 bacterial receptors that respond to CD-NTase signals. Structures of Cap4 reveal a promiscuous DNA endonuclease domain activated through ligand-induced oligomerization. Oligonucleotide recognition occurs through an appended SAVED domain that is an unexpected fusion of two CRISPR-associated Rossman fold (CARF) subunits co-opted from type III CRISPR immunity. Like a lock and key, SAVED effectors exquisitely discriminate 2'-5'- and 3'-5'-linked bacterial cyclicoligonucleotide signals and enable specific recognition of at least 180 potential nucleotide second messenger species. Our results reveal SAVED CARF family proteins as major nucleotide second messenger receptors in CBASS and CRISPR immune defense and extend the importance of linkage specificity beyond mammalian cGAS-STING signaling.

Keywords:

CARF; CBASS antiphage immunity; CD-NTase; SAVED; nucleotide second messenger

Links

PMID: 32544385

DOI: 10.1016/j.cell.2020.05.019

Lowey B, ➤Whiteley AT, Keszei AFA, Morehouse BR, Mathews IT, Antine SP, Cabrera VJ, Kashin D, Niemann P, Jain M, Schwede F, Mekalanos JJ, Shao S, Lee ASY, Kranzusch PJ. | Cell. 2020

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