View source for 30gb


==Cryo-EM structure of the PseCascade-TniQ-TnsC complex bound to PseTnsB-hook motifs==
<StructureSection load='30gb' size='340' side='right'caption='[[30gb]], [[Resolution|resolution]] 2.90&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[30gb]] is a 27 chain structure with sequence from [https://en.wikipedia.org/wiki/Escherichia_coli_K-12 Escherichia coli K-12] and [https://en.wikipedia.org/wiki/Pseudoalteromonas_sp._S983 Pseudoalteromonas sp. S983]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=30GB OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=30GB FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">Electron Microscopy, [[Resolution|Resolution]] 2.9&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=ATP:ADENOSINE-5-TRIPHOSPHATE'>ATP</scene>, <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene></td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=30gb FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=30gb OCA], [https://pdbe.org/30gb PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=30gb RCSB], [https://www.ebi.ac.uk/pdbsum/30gb PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=30gb ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/A0ABF7PQB9_9GAMM A0ABF7PQB9_9GAMM] 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
CRISPR-associated transposases (CASTs) achieve site-specific DNA integration by coupling the RNA-guided targeting action of a nuclease-deficient CRISPR-Cas system with the assembly of a Tn7-like transpososome complex (1,2) . Understanding the detailed mechanisms of this elaborate process is paramount to engineering CAST systems into programmable genetic tools (3-6) . The type I-F Pseudoalteromonas CAST ( Pse CAST) displays the highest activity in mammalian cells to date (7) and has been the subject of extensive directed evolution (8) , but efforts to rationally engineer further improvements have been hampered by critical gaps in our understanding of transpososome assembly and activation (9) . Here we use cryo-EM structural analysis, validated by DNA transposition assays, to visualize the Pse CAST system in a series of functional states that define the stepwise mechanism of RNA-guided DNA integration. The structure of a target DNA-bound Cascade-TniQ-TnsC complex reveals that conformational changes induced by R-loop formation are coupled to target DNA stabilization and TnsC heptamerization, which in turn recruits the TnsAB transposase via conserved interactions with its C-terminal tail. Finally, the structure of the 1.2 MDa Pse CAST transpososome holocomplex reveals specific TnsC-TnsB and TnsB-target DNA interactions that drive allosteric remodelling of the TnsB catalytic site to activate donor DNA integration. Together, these findings establish a unified structural and mechanistic blueprint for RNA-guided DNA integration and lay the foundation for engineering next-generation DNA insertion systems for genome editing applications.

Structural basis of RNA-guided DNA integration by type I CRISPR-associated transposases.,Finocchio G, Oberli S, Lampe G, Schmitz M, Sternberg SH, Jinek M bioRxiv [Preprint]. 2026 May 18:2026.05.18.725949. doi: , 10.64898/2026.05.18.725949. PMID:42239233<ref>PMID:42239233</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 30gb" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Escherichia coli K-12]]
[[Category: Large Structures]]
[[Category: Pseudoalteromonas sp. S983]]
[[Category: Finocchio G]]
[[Category: Jinek M]]
[[Category: Oberli S]]
[[Category: Schmitz M]]