Phosphorylation-dependent conformational change in the Keratin 19 head domain: Implications for filament assembly and binding to GSK3β and 14-3-3
- 1Daegu Gyeongbuk Institute of Science and Technology (DGIST)
Abstract
Keratins are intermediate filament (IF) proteins expressed in various cell types, playing a crucial role in mechanical support and signaling pathways. Keratin 19 (K19) is predominantly found in gut epithelia and early embryonic ectoderm. K19 interacts with signaling proteins such as GSK3{beta} and 14-3-3 to participate in cell signaling pathways. However, details on the binding sites of these proteins on K19, and specific molecular mechanisms governing these interactions, are lacking. Additionally, the N-terminal head domains of IFs including K19 are considered intrinsically disordered regions (IDRs), and their atomic-resolution structures are unavailable. Using NMR spectroscopy, we obtained the first solution structures of K19 head domain peptides. Structural models involving phosphomimetic peptides suggest a phosphorylation-dependent conformational change in the K19 head domain. The phosphomimetic S35E substitution alters the conformation of the head domain, affecting its association with keratin filaments and K19-binding partners. NMR spectral changes indicate that the S35E substitution affects the association of the K19 head domain to K8/K19 filaments and GSK3{beta}, whereas no significant binding changes were observed with 14-3-3{zeta} and 14-3-3{sigma}. Cell-based analyses further showed that the S35E mutation altered keratin filament organization and reduced the proximity between K19 and GSK3{beta} in 293T cells, whereas no significant change was observed in the proximity between K19 and 14-3-3{sigma}. Our findings provide insight into the structure-function relationship of the head domains in IF proteins with direct implications for the assembly of filaments and their role in signal modulation.
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BibTeX
@misc{ji2026phosphorylationdependent,
title = {{Phosphorylation-dependent conformational change in the Keratin 19 head domain: Implications for filament assembly and binding to GSK3β and 14-3-3}},
author = {Y. Ji and M. Jeong and J. Kim and J. Yeom and M. A. Han and C. Park and S.-H. Lee and E. Hong and Y. H. Ko and P. A. Coulombe and J. H. Kim and C.-H. Lee},
howpublished = {bioRxiv},
year = {2026},
month = nov,
doi = {10.64898/2026.11.06.764774},
url = {https://www.biorxiv.org/content/10.64898/2026.11.06.764774v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Phosphorylation-dependent conformational change in the Keratin 19 head domain: Implications for filament assembly and binding to GSK3β and 14-3-3
AU - Y. Ji
AU - M. Jeong
AU - J. Kim
AU - J. Yeom
AU - M. A. Han
AU - C. Park
AU - S.-H. Lee
AU - E. Hong
AU - Y. H. Ko
AU - P. A. Coulombe
AU - J. H. Kim
AU - C.-H. Lee
PY - 2026
DA - 2026/11/06
PB - bioRxiv
DO - 10.64898/2026.11.06.764774
UR - https://www.biorxiv.org/content/10.64898/2026.11.06.764774v1
AB - Keratins are intermediate filament (IF) proteins expressed in various cell types, playing a crucial role in mechanical support and signaling pathways. Keratin 19 (K19) is predominantly found in gut epithelia and early embryonic ectoderm. K19 interacts with signaling proteins such as GSK3{beta} and 14-3-3 to participate in cell signaling pathways. However, details on the binding sites of these proteins on K19, and specific molecular mechanisms governing these interactions, are lacking. Additionally, the N-terminal head domains of IFs including K19 are considered intrinsically disordered regions (IDRs), and their atomic-resolution structures are unavailable. Using NMR spectroscopy, we obtained the first solution structures of K19 head domain peptides. Structural models involving phosphomimetic peptides suggest a phosphorylation-dependent conformational change in the K19 head domain. The phosphomimetic S35E substitution alters the conformation of the head domain, affecting its association with keratin filaments and K19-binding partners. NMR spectral changes indicate that the S35E substitution affects the association of the K19 head domain to K8/K19 filaments and GSK3{beta}, whereas no significant binding changes were observed with 14-3-3{zeta} and 14-3-3{sigma}. Cell-based analyses further showed that the S35E mutation altered keratin filament organization and reduced the proximity between K19 and GSK3{beta} in 293T cells, whereas no significant change was observed in the proximity between K19 and 14-3-3{sigma}. Our findings provide insight into the structure-function relationship of the head domains in IF proteins with direct implications for the assembly of filaments and their role in signal modulation.
ER -