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| Title | Structure of human lymphoid-specific helicase HELLS in its autoinhibited state. |
|---|---|
| Journal, issue, pages | Nucleic Acids Res, Vol. 54, Issue 6, Year 2026 |
| Publish date | Mar 19, 2026 |
Authors | Gundeep Kaur / Ren Ren / Jisun Lee / John R Horton / Xing Zhang / Yang Gao / Taiping Chen / Xiaodong Cheng / ![]() |
| PubMed Abstract | Helicase, Lymphoid Specific (HELLS), also known as Lymphoid-Specific Helicase (LSH), is a member of the SNF2 chromatin-remodeling family that regulates DNA methylation and heterochromatin ...Helicase, Lymphoid Specific (HELLS), also known as Lymphoid-Specific Helicase (LSH), is a member of the SNF2 chromatin-remodeling family that regulates DNA methylation and heterochromatin organization. Unlike most chromatin remodelers, HELLS is catalytically inactive in its apo form and requires the DNA-binding protein CDCA7 for activation, though the underlying mechanism has remained unclear. Here, we combine biochemical, biophysical, and cryo-electron microscopy analyses to define the structural basis of HELLS autoinhibition. HELLS alone assembles into a hexameric (trimer of dimers) architecture stabilized by interactions between its N-terminal coiled-coil (CC) domain and ATPase Lobe-1, while ATPase Lobe-2 remains flexible and disengaged. The CC domain functions both as an oligomerization scaffold and as an autoinhibitory module that restricts catalytic activity. Binding of CDCA7 and DNA promotes formation of an active HELLS-CDCA7-DNA ternary complex. CDCA7 recognizes hemimethylated CpG dinucleotides in both B-form and non-B-form DNA and stimulates HELLS ATPase activity. Together, these findings reveal the mechanism of HELLS autoinhibition and its activation by CDCA7 and DNA, providing new insight into how the HELLS-CDCA7-DNA ternary complex maintains DNA methylation and heterochromatin integrity. |
External links | Nucleic Acids Res / PubMed:41954988 / PubMed Central |
| Methods | EM (single particle) |
| Resolution | 2.86 - 5.76 Å |
| Structure data | EMDB-73693, PDB-9z04: EMDB-73694: Structure of human lymphoid-specific helicase HELLS in its auto-inhibitory state EMDB-73695, PDB-9z06: ![]() EMDB-73696: Structure of human lymphoid-specific helicase HELLS in its auto-inhibitory state ![]() EMDB-73697: Focussed refinement map of ATPase lobe 2 of human lymphoid-specific helicase HELLS |
| Source |
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Keywords | DNA BINDING PROTEIN / lymphoid-specific helicase / SF2 chromatin remodeler / ICF syndrome / ATP-binding / Chromatin-binding |
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