RT @JoePetersLab: Our preprint is now published

RT @zhangf: We are excited to report the discovery of TIGRs, a widely-occurring RNA-guided system found in bacteria and their viruses. TIGR….

CRISPR-Cas systems are common in chromosomes and on mobile plasmids. Therefore, targeting arrays would provide a stable integration position facilitating vertical transmission while maintaining the ability to mobilize between bacteria for horizontal transmission. 10/10.

We did not find significant array degradation downstream the insertion. We suspect that integrating into a spacer in the arrays and keeping a small size allow these elements to not disrupt CRISPR-Cas system function. 9/10

Aligning the DNA sequences that flank the ends of the tRNA- and array-targeting elements revealed a conserved DNA motif 40 to 50 bp away from the transposons left ends. 8/10

Unlike the tRNA-targeting pathway from the closely related McCAST element, the array targeting element was not functional in E. coli and may need host factors not found in this heterologous host. 7/10.

AlphaFold3-generated structures of TnsD proteins from A. franciscana (AfTnsD, array-targeting) and M. californica (McTnsD, tRNA-targeting) suggest that the C-terminal region absent in AfTnsD corresponds to a helix-turn-helix domain (HTH) used for DNA binding. 6/10

Unlike most Tn7-like elements, array-targeting transposons do not accumulate cargo genes. This contrasts with what is found even with the closely related tRNA-targeting elements. 5/10

A distinct structural difference that co-occurs with the change in att site used between these two elements is a C-terminal motif found in the tRNA-targeting TnsD proteins that is absent in the array-targeting group. 4/10

A similarity tree of nonredundant TnsD/TniQ proteins revealed that the array-targeting transposons are phylogenetically close to TnsD-mediated tRNA-targeting transposons in this phylum, a group that includes validated I-D and I-B2 CAST. 3/10

We found a novel family of Tn7-like transposable elements in Cyanobacteria which display a preference for insertion within CRISPR arrays, suggesting a previously unrecognized functional interplay between Tn7-like elements and CRISPR-Cas systems. 2/10

Our preprint describing a family of Tn7-like transposons that evolved to target CRISPR repeats is now published at Mobile DNA #Tn7 #transposons #mobileDNA 1/10.

RT @JoePetersLab: Recent work from the lab from Laura Chacon @pomarros4 describing a family of Tn7-like transposons that evolved to target….

RT @biorxiv_molbio: A family of Tn7-like transposons evolved to target CRISPR repeats #biorxiv_molbio.

RT @JoePetersLab: It was a pleasure working with @PopoMicro on this review of CRISPR-Cas associated transposons (CAST). Hopefully it gives….

RT @JoePetersLab: This story involved many hands over many years led by @BertCorrea3 and @SaadleeS. Novel mechanisms of diversity generatio….