Biology subjects

Cirulli, A. E.

Publications and source records attributed to Cirulli, A. E..

2 recordsLinked to original sources

bioRxiv2025

A chromatin-associated pool of Aurora A controls kinetochore-microtubule attachments to ensure chromosome biorientation

Accurate chromosome segregation requires dynamic kinetochore-microtubule attachments that, under the regulation of Aurora family kinases, biorient and align replicated chromosomes. In C. elegans, Aurora A acts with the TPX2-related activator TPXL-1 to regulate these attachments and control spindle length. We show that, in addition to prominent spindle pole localization, TPXL-1-AurA has a chromatin-associated pool positioned between the sister kinetochores. Structural modeling and biochemical analysis support TPXL-1 directly recognizing the nucleosome acidic patch via an arginine anchor. Disrupting this interaction selectively removed chromatin-bound TPXL-1-AurA and caused chromosome missegregation, whereas elevation of the chromatin pool disrupted chromosome alignment. These opposing perturbations inversely affected kinetochore recruitment of the microtubule-binding Ska complex. These results support spatially distinct TPXL-1-AurA populations acting sequentially, with the spindle pole pool controlling spindle length by switching kinetochores out of a depolymerization-coupled state, and the chromatin pool controlling attachment stabilization to ensure biorientation prior to anaphase.

cell biology↗

bioRxiv2025

Bipartite chromatin recognition by Hop1 from two diverged holozoa

In meiosis, ploidy reduction is driven by a complex series of DNA breakage and recombination events between homologous chromosomes, orchestrated by meiotic HORMA domain proteins (HORMADs). Meiotic HORMADs possess a central chromatin binding region (CBR) whose architecture varies across eukaryotic groups. Here, we determine high-resolution crystal structures of the meiotic HORMAD CBR from two diverged aquatic holozoa, Schistosoma mansoni and Patiria miniata, which reveal tightly-associated PHD and winged helix-turn-helix (wHTH) domains. We show that PHD-wHTH CBRs bind duplex DNA through their wHTH domains, and identify key residues that disrupt this interaction. Combining experimental and predicted structures, we show that the CBRs PHD domains likely interact with the tail of histone H3, and may discriminate between unmethylated and trimethylated H3 lysine 4. Finally, we show that holozoa Hop1 CBRs bind nucleosomes in vitro in a bipartite manner involving both the PHD and wHTH domains. Our data reveal how meiotic HORMADs with PHD-wHTH CBRs can bind chromatin and potentially discriminate between chromatin states to drive meiotic recombination to specific chromosomal regions.

biochemistry↗