7x4p

Publication Abstract from PubMed

Purine-containing nucleotide second messengers regulate diverse cellular activities. Cyclic di-pyrimidines mediate anti-phage functions in bacteria; however, the synthesis mechanism remains elusive. Here, we determine the high-resolution structures of cyclic di-pyrimidine-synthesizing cGAS/DncV-like nucleotidyltransferases (CD-NTases) in clade E (CdnE) in its apo, substrate-, and intermediate-bound states. A conserved (R/Q)xW motif controlling the pyrimidine specificity of donor nucleotide is identified. Mutation of Trp or Arg from the (R/Q)xW motif to Ala rewires its specificity to purine nucleotides, producing mixed purine-pyrimidine cyclic dinucleotides (CDNs). Preferential binding of uracil over cytosine bases explains the product specificity of cyclic di-pyrimidine-synthesizing CdnE to cyclic di-UMP (cUU). Based on the intermediate-bound structures, a synthetic pathway for cUU containing a unique 2'3'-phosphodiester linkage through intermediate pppU[3'-5']pU is deduced. Our results provide a framework for pyrimidine selection and establish the importance of conserved residues at the C-terminal loop for the specificity determination of CD-NTases.

Crystal structure and functional implications of cyclic di-pyrimidine-synthesizing cGAS/DncV-like nucleotidyltransferases.,Yang CS, Ko TP, Chen CJ, Hou MH, Wang YC, Chen Y Nat Commun. 2023 Aug 21;14(1):5078. doi: 10.1038/s41467-023-40787-9. PMID:37604815^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.