9NTO

Structure of Cap9-CdnD complex containing NDG modification

Summary for 9NTO

• Entry DOI: 10.2210/pdb9nto/pdb
• Descriptor: CdnD, Cap9, ADENOSINE MONOPHOSPHATE, ... (7 entities in total)
• Functional Keywords: cd-ntase, quec, cbass, antiviral protein
• Biological source: Hyphomicrobiales; More
• Total number of polymer chains: 2
• Total formula weight: 55370.81

Authors

Wassarman, D.R.,Pfaff, P.,Paulo, J.A.,Gygi, S.P.,Shokat, K.M.,Kranzusch, P.J. (deposition date: 2025-03-18, release date: 2025-05-07)

Primary citation

Wassarman, D.R.,Pfaff, P.,Paulo, J.A.,Gygi, S.P.,Shokat, K.M.,Kranzusch, P.J.
Deazaguanylation is a nucleobase-protein conjugation required for type IV CBASS immunity.
Biorxiv, 2025

PubMed Abstract: 7-deazapurines are nucleobase analogs essential for nucleic acid modifications in nearly all cellular life. Here, we discover a role for 7-deazapurines in protein modification within type IV CBASS anti-phage defense and define functions for CBASS ancillary proteins Cap9 and Cap10 in nucleobase-protein conjugation. A structure of Cap10 reveals a tRNA transglycosylase-family enzyme remodeled to bind the modified N-terminus of a partner cGAS/DncV-like nucleotidyltransferase linked to a 7-amido-7-deazaguanine (NDG) nucleobase. The structure of Cap9 explains how this QueC-like enzyme co-opts a 7-deazapurine biosynthetic reaction mechanism for NDG conjugation. We demonstrate that Cap9, Cap10, and NDG conjugation are essential for host defense against phage infection. Our results define a previously unknown 7-deazapurine protein modification and explain how nucleobase biosynthetic machinery has been repurposed for antiviral immunity.

PubMed: 40236162
DOI: 10.1101/2025.04.06.647259

Experimental method

X-RAY DIFFRACTION (2.15 Å)