Biology subjects

Sotelo-Parrilla, P.

Publications and source records attributed to Sotelo-Parrilla, P..

4 recordsLinked to original sources

bioRxiv2026

The structure of the apo-PIWI HSP90 complex

PIWI proteins are members of the Argonaute family and together with piRNAs protect metazoan germlines from transposons. PIWI proteins adopt a bi-lobed architecture with a central RNA-binding channel. HSP90 function has been linked to piRNA biogenesis, but the precise molecular mechanism is unresolved. Using the mammalian embryonic piRNA pathway as a model system, we find compelling evidence for the existence of PIWIL2- (MILI-) and PIWIL4- (MIWI2-) HSP90 complexes in foetal testis. We purify apo-PIWIL4-HSP90 from cells and determine its structure by cryo-electron microscopy. Distinct from piRNA-bound PIWI, apo-PIWIL4 adopts a unique and open conformation. The HSP90 dimer binds and unfolds PIWIs linker 1 domain. PIWIL4s N domain and the RNA-binding PAZ-MID-PIWI module are placed on opposite sides of the HSP90 dimers lumen. We further demonstrate that PIWI-HSP90 complexes, the open apo-PIWI conformation, and the HSP90 lumen-binding peptide are conserved features of PIWI proteins.

molecular biology↗

bioRxiv2025

Chromatin Protection by the Chromosomal Passenger Complex

The chromosomal passenger complex (CPC; Borealin-Survivin-INCENP-Aurora B kinase) ensures accurate chromosome segregation by orchestrating sister chromatid cohesion, error-correction of kinetochore-microtubule attachments and spindle assembly checkpoint. Correct spatiotemporal regulation of CPC localization is critical for its function. Phosphorylations of Histone H3 Thr3 and Histone H2A Thr120 and modification-independent nucleosome interactions involving Survivin and Borealin contribute to CPC centromere enrichment. However, mechanistic basis for how various nucleosome binding elements collectively contribute to CPC centromere enrichment and whether CPC has any non-catalytic role at centromere remain open questions. Combining a high-resolution cryoEM structure of CPC-bound H3Thr3ph nucleosome with atomic force microscopy and biochemical and cellular assays, we demonstrate that CPC employs multipartite interactions involving both static and dynamic interactions, which facilitate its engagement at nucleosome acidic patch and DNA entry-exit site. Perturbing the CPC-nucleosome interaction compromises protection against MNase digestion in vitro, as well as the dynamic centromere association of CPC and centromeric chromatin stability in cells. Our work provides a mechanistic basis for the previously unexplained non-catalytic role of CPC in maintaining centromeric chromatin critical for kinetochore function.

biochemistry↗

bioRxiv2024

PLK1-Mediated Phosphorylation Cascade Activates the Mis18 Complex to Ensure Centromere Inheritance

Accurate chromosome segregation requires the attachment of spindle microtubules to centromeres, which are epigenetically defined by the enrichment of CENP-A nucleosomes. During DNA replication, existing CENP-A nucleosomes undergo dilution as they get redistributed among the two DNA strands. To preserve centromere identity, CENP-A levels must be restored in a cell-cycle controlled manner orchestrated by the Mis18 complex. Here we provide a comprehensive mechanistic basis for PLK1-mediated licensing of CENP-A loading. We demonstrate that PLK1 interacts with Mis18 and Mis18BP1 subunits of the Mis18 complex by recognising self-primed phosphorylations of Mis18 (S54) and Mis18BP1 (T78 and S93) through its Polo-box binding domain. Disrupting these PLK1 phosphorylations perturbed the centromere recruitment of HJURP and new CENP-A loading. Biochemical and functional analyses show that phosphorylation of Mis18 and subsequent PLK1 binding is required to activate the Mis18/{beta} complex for robust Mis18/{beta}-HJURP interaction. Thus, our study reveals key molecular events underpinning the licensing role of PLK1 in ensuring accurate centromere inheritance. One-Sentence SummaryPLK1 phosphorylation cascade licenses CENP-A loading by facilitating HJURP centromere recruitment via Mis18/{beta} activation.

cell biology↗

bioRxiv2023

Oryza genera-specific novel Histone H4 variant predisposes H4 Lysine5 Acetylation marks to modulate salt stress responses

Paralogous variants of canonical histones guide accessibility to DNA and function as additional layers of genome regulation. Across eukaryotes, the occurrence, mechanism of action and functional significance of several variants of core histones are well known except that of histone H4. Here we show that a novel variant of H4 (H4.V), expressing tissue-specifically among members of Oryza genera, mediates specific epigenetic changes contributing majorly to salt tolerance. H4.V was incorporated to specific chromosomal locations where it blocked deposition of active histone marks. Under salt stress, large scale re-distribution of H4.V enabled incorporation of stress dependent histone H4 Lysine5 Acetylation (H4K5Ac) marks. Mis-expression of H4.V led to defects at morphological level especially in reproductive tissues, and in mounting stress responses. H4.V mediated these alterations by condensing chromatin at specific genomic regions as seen with cryo-EM structure of reconstituted H4.V containing nucleosomes. These results not only uncovered the presence of a H4 variant in plants, but also a novel chromatin regulation of stress responses that might have contributed to success of semi-aquatic Oryza members under variable water-limiting conditions. One-line summaryHistone H4 variant predisposes chromatin for stress responses O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=199 SRC="FIGDIR/small/551207v1_ufig1.gif" ALT="Figure 1"> View larger version (53K): org.highwire.dtl.DTLVardef@101fa0forg.highwire.dtl.DTLVardef@c7fda9org.highwire.dtl.DTLVardef@1de9a0aorg.highwire.dtl.DTLVardef@1532641_HPS_FORMAT_FIGEXP M_FIG C_FIG

plant biology↗